A and B can do a piece of work in 20 days. After 12 days, A leaves and B completes the remaining work in 10 days. A alone can complete the work in how many days?
Show answer & explanation
Correct answer: B
Explanation
Work done by A and B in 1 day = 1/20
Work done in 12 days = 12/20 = 3/5
Remaining work = 1 - 3/5 = 2/5
B completes this remaining work in 10 days.
B's 1-day work = (2/5) ÷ 10 = 1/25
A + B = 1/20
A = 1/20 - 1/25
= 5/100 - 4/100
= 1/100
Therefore, A alone will complete the entire work in 100 days.