A can do a work in 10 days, B can do the same work in 15 days. If they work together, how long will it take them to finish the work ?

A 4

B 8

C 6

D 10

Correct Answer: Option C

Solution: \(\frac{{10 \times 15}}{{10 + 15}} = \frac{{10 \times 15}}{{25}}\) = 6 days.