A and B can finish a piece of work in 8 days and 12 days respectively. Together they start the work but after few days A left the job. After how many days had A left the job if B finished the remaining work in 2 days?

4

Total work = efficiency × number of days

Work done by B in 2 days = 2 × 2 = 4

Remaining work = 24 - 4 = 20

Total efficiency of A and B = 2 + 3 = 5

Time taken when A & B worked together  = \(\frac{20}{5}\) = 4 days

Hence, A left the work after 4 days