A can finish a work in 18days and B can do the same work in half the time taken by A. Then, working together what part of the same work they can finish in a day?	Choose the correct choice from the following choices.
A) 1 / 2	B) 1 / 3	C) 1 / 6	D) 2 / 5	E) 2 / 9

Rationale: 1 days work of a + b = ( 18 + 9 ) / 18 * 9 = 1 / 6 answer is c
Answer: C