A and B together can complete a piece of work in 4days. If A alone can complete the same work in 12days, in how many days, in how many days can B alone complete that work? Answers
A) 6	B) 8	C) 10	D) 12	E) 5

Rationale: "( a + b ) ' s 1 day ' s work = 1 / 4 a ' s 1 day ' s work = 1 / 12 b ' s 1 days ' s work = ( 1 / 4 ) - ( 1 / 12 ) = 1 / 6 hence , b alone can complete the work in 6 days . answer is a"
Answer: A