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. 4000. With the help of C, they completed the work in 3 days. How much is to be paid to C?	Choose the correct choice.
A) s . 375
B) s . 400
C) s . 500
D) s . 800
E) s . 850

Rationale: "c ' s 1 day ' s work = 1 / 3 - ( 1 / 6 + 1 / 8 ) = 1 / 3 - 7 / 24 = 1 / 24 a ' s wages : b ' s wages : c ' s wages = 1 / 6 : 1 / 8 : 1 / 24 = 4 : 3 : 1 c ' s share ( for 3 days ) = rs . ( 3 * 1 / 24 * 4000 ) = rs . 500 answer = c"
Answer: C