How much does the baby weigh if the mother weighs 100 pounds more than the combined weight of the baby and the dog, and the dog weighs 60 percent less than the baby?
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Posted 19 June 2013 - 02:32 PM
Spoiler for The baby is..25 lbs
nice work! Please elaborate on your answer.
Let b = baby's weight, d = dog's weight, w = woman's weight...
if the mother weighs 100 pounds more than the combined weight of the baby and the dog
EQUATION 1: b + d + 100 = w
the dog weighs 60 percent less than the baby
EQUATION 2: d = 0.4*b
and then from the picture, we know
EQUATION 3: b + d + w = 170
Then just solve the system
Substitute equation 2 into equations 1 and 3:
1) b + 0.4b + 100 = w and 3) b + 0.4b + w = 170
1) 1.4b + 100 = w and 3) 1.4b + w = 170
Then substitute equation 1 into equation 3:
1.4b + 1.4b + 100 = 170
Solve for b:
2.8b = 70
b = 25
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