B alone can finish a piece of work in 15 days, but with A’s help, they complete it in 6 days. In how many days can A alone finish the work?
Show answer & explanation
Correct answer: B
Explanation
B's 1-day work efficiency = 1/15
Combined 1-day work efficiency of A and B = 1/6
Therefore, A's 1-day work efficiency = 1/6 - 1/15
= (5 - 2)/30
= 3/30
= 1/10
So, A alone will complete the work in = 10 days