Question

P and Q together can complete a piece of work in 4 days. If P alone can complete the same work

in 20 days, in how many days can Q alone complete that work?​

Answer 1

Let total work done by P and Q beX
Work done by both in 4 days is X
Work done by both in 1 day isX/4
Work done by P in 20 days is X
Work done by P in 1 day is X/20
Work done by P in 1day + work done by Q in 1 day = work done by both in 1 day
Work done by Q in 1 day = x/4 -x/20
= 4x/20 = x/5
Days taken by Q to do x/5 work is 1
Days taken by Q to do x work is = 5
Hence alone Q takes 5 days