A can complete a certain work in 35 days and B can complete the same work in 15 days. They worked together for 7 days, then B left the work. In how many days will A alone complete 60% of the remaining work?

7

A = 35 days, B = 15 days,

⇒ A + B worked for 7 days = (3 + 7) x 7 = 70 units.  ..(Efficiency × Days = Total work)

⇒ Then B left, 

⇒ Then remaining work = 105 - 70 = 35 units.

⇒ 60% of 35 = 21 units.

⇒ Time taken by to complete 21 units of work = \(\frac{21}{3}\) = 7 days.  ..(\(\frac{Work}{Efficiency}\) = Time)