Question

A is thrice as good a workman as B. B takes 60 days more than A to finish a piece of work. The time in which they can do it working together is (a) 25 days (b) 30 days (c) 27 days (d)22 1/2 days

Answer 1

so given A = 3B
so the work which is done by a is x and that work is done by b is 3x
given b takes x + 60 days to complete a work
so 3x = 60 + x ⇒ x = 20
so A can do work in  20 days 
and B can do work in 20 + 60 = 80 days
so both can do the work in A + 3A = 80 + 20 days
so A = 25 days 
so a) 25 days is the answer

ANSWER