Ratio of times taken by A and B = 1 : 3

The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.

If difference of time is 2 days, B takes 3 days.

If difference of time is 60 days, B takes (3/2) x 60 = 90 days

So, A takes 30 days to do the work.

A's 1 day's work = 1/30

B's 1 day's work = 1/90

(A + B)'s 1 day's work = (1/30) + (1/90) = 4/90 = 2/45

=> A and B together can do the work in 45/2 = 22 (1/2) days