Question

An old brainteaser by the Central Asian scholar Biruni (973−1048): If 10 dirhams (a unit of currency) earn 5 dirhams of profit in 2 months, how much profit will 8 dirhams earn in 3 months?

Answer 1

27 Dirhams is how much 8 Dirhams would make in 3 months.

Answer 2

6 dirhams is the profit it will make.