A and B can compete a piece of work in 18 days. They worked together for 12 days and then A left. B alone finished the work in 15 days. If Rs. 1500 be paid for the work then A's share is:

Explanation:-

A and B can complete the work in 18 days, work rate = $$\frac{{100}}{{18}}$$ = 5.55% per day
They together can complete the work in 12 days = 5.55 × 12 = 66.66%
Now, A leaves and B takes another 15 days to complete the whole work, Work rate of B = $$\frac{{33.33}}{{15}}$$   = 2.22% per day
B work for (12 + 15) = 27 days
So, Work done by B in 27 days = 2.22 × 27 = 60% And So 40% work is done by A. so there share should be 60% and 40% ratio.
A's share = 40% of 1500 = Rs. 600