A can do a piece of work in 3 days of 5 hours each and B alone can do it in 5 days of 3 hours each.how long will they take it to do working together
3/4 hours a day?  Options
A) 6 days
B) 5 days
C) 10 days
D) 9 days
E) 8 days

Rationale: a ' s work per hour = 1 / 15 b ' s work per hour = 1 / 15 a & b ' s work per hour together = ( 1 / 15 ) + ( 1 / 15 ) = 2 / 15 so a & b together complete the work in 15 / 2 hours . . . if they work 2 1 / 2 = 5 / 2 hours a day , it will take ( 15 / 2 ) / ( 3 / 4 ) days = 10 days . . . answer : c
Answer: C