a , b , and c were to be paid in proportion to the part of work they did while working on the same piece of work . a and b individually can finish the piece of work in 12 days and 15 days respectively . they worked together for 5 days and then c completed the remaining work all alone . if $ 810 was the net sum to be paid for the entire work , what was the average daily wage of b ?  Select:
A) $ 144
B) $ 90
C) $ 60
D) $ 54
E) $ 48

Rationale: the correct answer is d .
Answer: D