10 men, working 7 hours a day can complete a work in 18 days. How many hours a day must 15 men work to complete the same work in 12 days?  Choose the correct choice from the following choices.
A) 6	B) 7	C) 8	D) 9	E) 10

Rationale: the number of hours required to complete the work is 10 * 7 * 18 = 1260 15 × 12 × ( x ) = 1260 x = 7 the answer is b .
Answer: B