Question

A and B together can do a piece of work in 6 days, A alone can do it in 9 days. HOW LONG B WILL TAKE TO FINISH IT

Answer 1

A and B can together do (1/6)th part of the work in one day.

A alone can do (1/9)th part of the work in one day.

Let B can do the whole piece of work in x days, so that B can do (1/x)th part of the work in one day.

So, in one day, A and B together can do (1/9) + (1/x) = (1/6) part of the work. So,

1/x = 1/6 - 1/9

1/x = (9 - 6) / (9 × 6)

1/x = 1/18

Therefore, x = 18.

I.e. , B alone can finish the work in 18 days.