A and B can finish a certain job in 28 and 35 days, respectively. They started working together, but A left after a while, and B managed to complete the remaining work in 17 days. How many days did A work before leaving?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 8 days.
A’s rate = 1/28
B’s rate = 1/35
Let A work for d days, then B works for (d + 17) days.
⇒ 5d + 4(d + 17) = 140
⇒ 5d + 4d + 68 = 140
⇒ 9d = 72
⇒ d = 72/9 = 8 days