[Guest]

3 friends met at an outdoor concert.

Adam brought 7 beers and 4 sandwiches.

Brian brought 5 beers and 5 sandwiches.

Carl brought nothing.

The friends agreed to share what they had, and so they did. They shared what they had equally. After the concert all was consumed, and Carl gave them 30 brainars (national BrainDen currency) to pay for his share according to the standard BrainDen price of beers and sandwiches. After a short debate Adam kept 15 brainars, and gave Brian the other 15 brainars.

What are the standard BrainDen prices of beers and sandwiches?

Edited April 12, 2009 by uhre

[andromeda]

Finally a math that I can grasp!!

Beer = 1 brainar

Sandwich = 2 brainars

I totally feel like drinking a beer right now

Welcome to the Den!

x - beer

y - sandwich

7x+4y=15

5x+5y=15

From the first equation I get that x=(15-14y)/7

when I put that in the second equation I get that y=2

and then I put 2 instead of y in the first equation and I get that x=1

EDIT: I just realized that I have calculated it as if the third friend paid for everything... I knew it was too good to be true. Back to my notes

Edited April 12, 2009 by andromeda

[Guest]

That's kind of an unconcealed spoiler, isn't it?

[andromeda]

That's kind of an unconcealed spoiler, isn't it?

You mean my edit! Sorry... I didn't think it was important to put it in a spoiler. I'm quite a spoiler freak myself, and I didn't realize... sorry. My time for edit has run out so I can't change it anymore. It works more like a hint so it's not a big giveaway... I think

EDIT: OK here's the real solution I think:

Beer = 3 brainars

Sandwich = 6 brainars

I have divided the previous equations with 3 (the left side I mean)!

I never do math problems so I was a bit hasty to be the first one to solve this one

Edited April 12, 2009 by andromeda

[DudleyDude]

I come up with:

beer = 3 brainars

sandwich = 6 brainars

I simply assumed that both Adam and Ben gave 1/3 of each of their goods to their 2 friends. This would give each person 4 beers and 3 sandwiches.

Since Carl paid 30 brainars for his portion, we have:

4b + 3s = 30

Brian supplied 5/3 beers and 5/3 sandwiches to Carl and received 15 brainars. This gives us:

5/3b + 5/3s = 15.

I don't like fractions so I multiplied by 3 to get:

5b + 5s = 45

So, 2 equations of 2 unknows:

4b + 3s = 30 -> multiply by 5

5b + 5s = 15 -> multiply by -3

20b + 15s = 150

-15b - 15s = -135 -> add the 2 equations to get

5b = 15 -> b = 3 -> plug back into one of the first equations

5(3) + 5s = 45 -> 15 + 5s = 45 -> 5s = 30 -> s=6

[Gmaster479]

Okay let me have a stab at this

In total, there are 12 beers and 9 sandwiches. Dividing the beers and sandwiches up for the 3 guys gives our friend Carl 4 beers and 3 sandwiches.

So using this information we set up the equation:

4b + 3s = $30

Also since the 2 guys who brought the food got $15 each, we need to make sure that whoever the food came from gets paid exactly half of the $30.

Based on this, we get that Carl took 3 beers worth $3 from Adam and a sandwich worth $6 from Adam totaling $15.

Then Carl took 2 sandwiches and a beer from Brian, which made a total of $15.

So s=6, b=3 and we can also infer that Brainars are worth more than the American Dollar!

[Guest]

Sandwhichs=2 Beer=1

7x+4y 5x+5y

----- x -----

15 15

messed up on cross multiplying in spoiler

Edited April 12, 2009 by Artem1620

[Guest]

Sandwiches are 6 brainars and beers are 3. I dont feel like posting the math as just did it in my head

[Guest]

Beer is 2 Sandwiches are 4

[Guest]

Beers cost one dollah and sandwiches cost 2 dollah.

1) 7b + 4s = 15

2) 5b + 5s = 15

Using subtractive elimination...

(5b + 5s = 15)

-(7b + 4s = 15)

_____________

-2b + s = 0

which is the same thing as: s = 2b

Substitute...

s = 2b

5b + 5s = 15

5b + 5(2b) = 15

5b + 10b = 15

15b = 15

~[b = 1]~

5(1) + 5s = 15

5 + 5s = 15

5s = 10

~[s = 2]~

(this is the long, but surefire, way to solve these kinds of riddles)

[Guest]

This is the only one that's right.

5 x 1 beers = 5, 5 x 2 sand = 10 = 5 + 10 = 15

7 x 1 beers = 7, 4 x 2 sand = 8 = 7 + 8 = 15

------

30 BrainDens total = 30

1 BrainDen/beer

2 BrainDens/sandwich

Edited April 13, 2009 by Deacon

[Guest]

answer...

b = beer

s = sandwich

br = symbol for brainar

3b + 1s = 15 ----------- (eq1)

1b + 2s = 15 => 3b + 6s = 45 -------- (eq2)

4b + 3s = 30

From eq2 - eq1

5s = 30

---------

S = 6 br

b = 3 br

[Guest]

Each person gets 4 beers and 3 sandwiches so you know 4b + 3s = 30

Since Adam and Brian split the 30 dollars they were given, you know that 7b + 4s = 5b + 5s

and by combining like terms you get 2b = s

Substitute that into the original equation you get 4b +3(2b) = 30 and solving that you get 10b = 30 and then b = 3.

Now solve for 's' 4(3) + 3s = 30 and then 3s = 18 and then s = 6

beer = 3

sandwich = 6

Edited April 13, 2009 by raoulrashiki

[Guest]

Beer is 2 Sandwiches are 4

Now since half of each of the peoples food was worth 15br we can assume the full amount was worth 30br, unless during their debate one person was twice the other persons size then there are other variables.

So

7b+4s=30

also

5b+5s=30

So we can make the conclution

7b + 4s=5b + 5s

-5b -5b

2b + 4s=5s

-4s -4s

2b=s

putting this back into the first equation

7b + 4s=30

knowing that s = 2b

7b + 4(2b)=30

7b + 8b=30

15b=30

b=2

5b + 5s=30

5(2) + 5s=30

5s=20

s=4

or you could have done

5b + 5s=30

5(.5s) + 5s=30

2.5s + 5s=30

7.5s=30

s=4

All in all just pay attention to the wording of the question then its a simple equation.

[Guest]

2 Brainars = Beer

4 Brainars = Sandwich.

Cause since the Carl paid 30 it means each of them had an equal share of 30 Brainars each.. hence i came up with 2 and 4...

[Guest]

3 friends met at an outdoor concert.

Adam brought 7 beers and 4 sandwiches.

Brian brought 5 beers and 5 sandwiches.

Carl brought nothing.

The friends agreed to share what they had, and so they did. They shared what they had equally. After the concert all was consumed, and Carl gave them 30 brainars (national BrainDen currency) to pay for his share according to the standard BrainDen price of beers and sandwiches. After a short debate Adam kept 15 brainars, and gave Brian the other 15 brainars.

What are the standard BrainDen prices of beers and sandwiches?

Cheers for this- I'm trying it out on all my brainiac friends! - angelcatrom

Edited April 13, 2009 by angelcatrom

[Guest]

You mean my edit! Sorry... I didn't think it was important to put it in a spoiler. I'm quite a spoiler freak myself, and I didn't realize... sorry. My time for edit has run out so I can't change it anymore. It works more like a hint so it's not a big giveaway... I think

EDIT: OK here's the real solution I think:

Beer = 3 brainars

Sandwich = 6 brainars

I have divided the previous equations with 3 (the left side I mean)!

I never do math problems so I was a bit hasty to be the first one to solve this one

Yes, I was referring to your edit. Since the math on this puzzle is not that complex, the intended puzzle was to figure out what you almost gave away. Anyway, apology accepted - and your 'real solution' is indeed the real solution.

The OP states that Adam brought 7 beers, and 4 sandwiches, while Brian brought 5 beers and 5 sandwiches - for a total of 12 beers and 9 sandwiches.

Carl didn't bring anything and instead paid for what he ate/drank.

So how should Adam and Brian share this payment?

Well, one obvious - but also a little hasty - approach is to setup the following equations:

7b + 4s = 15 & 5b + 5s = 15

Solve the equations for the result: Beer = 1 and Sandwiches = 2

While this seems to work out it does not distribute the payment fairly.

Consider the contribution each friend made to give Carl his share:

- Adam consumed 4 beers and 3 sandwiches of his own, and contributed 3 beers and 1 sandwich to Carl's share

- Brian consumed 4 beers and 3 sandwiches of his own, and contributed 1 beer and 2 sandwiches to Carl's share

The 30 brainars paid by Carl should be distributed to Adam and Brian according to their contribution, so:

3b + 1s = 15 & 1b + 2s = 15

Solve the equations for the result: Beer = 3 and Sandwiches = 6

So

- 3 brainers for each beer, and

- 6 brainers for each sandwich

...is the intended answer, and - as far as I'm concerned - the only fair answer.

[Guest]

3 friends met at an outdoor concert.

Adam brought 7 beers and 4 sandwiches.

Brian brought 5 beers and 5 sandwiches.

Carl brought nothing.

The friends agreed to share what they had, and so they did. They shared what they had equally. After the concert all was consumed, and Carl gave them 30 brainars (national BrainDen currency) to pay for his share according to the standard BrainDen price of beers and sandwiches. After a short debate Adam kept 15 brainars, and gave Brian the other 15 brainars.

What are the standard BrainDen prices of beers and sandwiches?

Sandwich = 6 brainars

Beer = 3 brainars

[andromeda]

Sandwich = 6 brainars

Beer = 3 brainars

Hi Nikhilesh! Welcome to the Den!

That is the correct answer, and it has already been posted before, however, next time you put down your answer to some riddle please use spoilers (on your left after you click on the add reply button). That way you won't spoil the enjoyment of solving the riddle for other members!

Have fun