A and B working together can finish a piece of work in 12 days

A and B working together can finish a piece of work in 12 days while B alone can finish it in 30 days. In how many days can A alone finish the work?

  1. 18 days
  2. 20 days
  3. 24 days
  4. 25 days

Answer

Let the work be 60 units. (LCM of 12 and 30)

A and B working together can finish 60 units of work in 12 days.

So, one day work of A and B = 5 units

B alone can finish 60 units of work in 30 days.

So, one day work of B alone = 2 units

One day work of A alone = 5 units - 2 units = 3 units

A lone can complete 60 units of work in 20 days.

The correct option is B.