'A' alone can do a piece of work in 10 days and 'B' alone can do it in 15 days. 'A' and 'B' undertook to do the work for ₹42,000. With the help of 'C', they completed the work in 5 days. How much (in ₹) is to be paid to C?
1
21,000
2
15,000
3
7,000
4
More than one of the above
5
None of the above