A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is : Choose the most appropriate option:	A) 1/4	B) 1/10	C) 7/15	D) 8/15	E) 9/15
Explanation:   A's 1 day's work =	1/15   B's 1 day's work =	1/20   (A + B)'s 1 day's work =	(1/15 + 1/20)=7/60   (A + B)'s 4 day's work =7/60 X 4 = 7/15   Therefore, Remaining work =	1-7/15 =8/15   ANSWER IS 8/15
<result>D</result>
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :