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 correct choice from the following
A) 8/15 B) 7/15 C) 2 D) 1/15 E) 1/10
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.   8/15nswer: Option 8/15
<result>A</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 :