Question

A and b together can do a piece of work in 12 days.if a can complete the work in 20 days

Answer 1

Both A and B can complete 1/12th work in one day

So A+B=1/12 in one day

A alone can complete 1/20 th work

A=1/20 in one day

Now B alone how much work can complete

(1/20)+B=1/12

B =(1/12)-(1/20)

L.C.M of 12 and 20 is 60

So B=( (5–3)/60)

B=2/60=1/30

So alone can complete 1/30th work in one day

B alone can complete the work in 30 days

Answer 2

A can do it in 20 days

1 day work of A = 1/20

A and B together in 12 days

1 day work of A+B = 1/12

1 day work of B = 1/12 - 1/20 = (5-3) / 60 = 2/60 = 30

So B can do it in 30 days