A is thrice as good a workman as B and takes 60 days less than B for doing a job. The time in which they can do it together is:

Explanation

If A can finish a work = x days B will do this work = 3x days From question, A – B = 3x – x = 60 Þ x = 30 A = 30 days, B = 90 days A’s 1 day work + B’s 1 day work = 1 1 4 + = 30 90 90 So, A and B working together can complete work = 90 4 = 22.5 days 10%­ 5%­ ¾¾¾® cost to B ¾¾¾® cost to C