A and B working alone can complete a work in 8 days and 12 days. respectively. They started working together, but A left 2 days before completion of the work. In how many days was the work completed ?

6

A = 8 days, B = 12 days,

⇒ Last 2 days work done by B = 2 x 2 = 4 units   ..(Efficiency × Days = Work)

⇒ Remaining work = 24 - 4 =20 units.

⇒ Work done by A + B = 3 + 2 = 5 units.

⇒ \(\frac{Remaining   work}{5}\) + last 2 days = \(\frac{20}{5}\) + 2 = 6 days

Therefore, the work was completed in 6 days.