A is thrice as good a workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
Answer: B
Let the time taken by A be T days. Then B takes 3T days. The difference in time is \(3T - T = 2T = 60\) days. So, \(T=30\). A takes 30 days and B takes 90 days. Their combined one day's work is \(1/30 + 1/90 = (3+1)/90 = 4/90 = 2/45\). So, together they will take 45/2 = 22.5 days.