In general to solve problems of this type, one can proceed as follows:
Prepare a data table
^ hens eggs days
| 1.5.... 1.5 ....1.5
| x .......18...... 3
Draw an arrow from the unknown x to the known value (in this case of hens). The value of x is then obtained by multiplying the known value by the ratios of the other quantities taken in the same direction of the arrow if they are directly proportional with respect to the unknown x, in the opposite direction if inversely porportional. In this case the number of eggs is directly proportional (more hens, more eggs), the days are inversely proportional (more days, less hens necessary to lay a certain number of eggs).
x = 1.5x(18/1.5)x(1.5/3) = 9.
For the typists problem we have:
^ typists pages minutes
In this case the pages are directly proportional (more typists, more pages), the minutes inversely proportional (more typists, less time to type a certain number of pages). So:
x = 2x(18/2)x(2/18) = 2.
(I couldn't find a better method of drawing the arrow)
well your wrong...the problem is how many typist will it take to type 18 pages in six minutes.....the answer is 6typists