A is twice as good as B. And together they finish a piece of work in 20days. In how many days will A alone finish the work
Choose the correct answer:	A) 30	B) 25	C) 12	D) 10	E) 32

Rationale: "( a ' s 1 day work ) : ( b ' s 1 day work ) = 2 : 1 a + b 1 day work = 1 / 20 a ' s 1 day work = ( 1 / 20 ) * ( 2 / 3 ) = 1 / 30 a alone can finish the work in 30 days answer is a"
Answer: A