The task is to generate the correct answer for a given math problem.

[Q]: Problem: the length of a rectangle is increased by 15 % and its breadth is decreased by 20 % . what is the effect on its area ?
[A]: 920


[Q]: Problem: a contractor undertook to do a piece of work in 18 days . he employed certain number of laboures but 9 of them were absent from the very first day and the rest could finish the work in only 6 days . find the number of men originally employed ?
[A]: 4.5


[Q]: Problem: the balance of a trader weighs 10 % less than it should . still the trader marks up his goods to get an overall profit of 20 % . what is the mark up on the cost price ?
[A]:
8 %