A alone can do a piece of work in 6 days and B alone in 8 days. A and B undertook to do it for Rs. 3200. With the help of C, they completed the work in 3 days. How much is to be paid to C  Pick one:
A) rs . 300	B) rs . 400	C) rs . 500	D) rs . 600	E) none of these

Rationale: "explanation : c ' s 1 day ' s work = 1 / 3 − ( 1 / 6 + 1 / 8 ) = ( 1 / 3 − 7 / 24 ) = 1 / 24 a : b : c = 1 / 6 : 1 / 8 : 1 / 24 = 4 : 3 : 1 c ′ sshare = 1 / 8 ∗ 3200 = 400 option b"
Answer: B