2017 · Q28
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 ?
Elementary MathematicsTime and Work
- A18 days
- B20 days
- C24 days
- D25 days
Explanation
Combined rate 1/12 per day; B's rate 1/30. A's rate = 1/12 − 1/30 = 3/60 = 1/20 per day, so A alone takes 20 days: option B.