A and B undertake to do a piece of work for Tk. 18,750. A can do it in 20 days and B can do it in 30 days. With the help of C, they finished it in 8 days. How much C should be paid for his work in proportion?

A and B undertake to do a piece of work for Rs. 18,750

A can do it in 20 days and B can do it in 30 days.

Concept used:
Total work = LCM of the time taken by workers alone
Share of the amount is in the ratio of efficiency

Calculation:
LCM of 20 and 30 is 60 i.e total work
So, efficiency of A and B is 60/20 = 3, 60/30 = 2
Efficiency of A + B + C = 60/8 = 7.5
Efficiency of C = 7.5 - 3 - 2 = 2.5