A can complete the work in 12 days, B in 15 days. Find the extra time taken by B to complete the work if A left 2 days before the scheduled completion of work?

Solution (By Examveda Team)

A can complete the work in 12 days.
Work rate of A = 100/12 = 8.33 % per day.
B can complete the work in 15 days.
Work rate of B = 100/15 = 6.66 % per days.
Work rate of A and B together = (A + B) = 8.33 + 6.66 = 15% per day.
Scheduled work completed in = 100/15 = 6.66 days.
But two days before A left,
Rest work for B,
= 15*2 = 30% (Approx)
Now, B can complete this work in,
30/6.66 = 4.50 days.
So, Total days needed to complete,
6.66 - 2 + 4.50 = 9.16 days.