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) 1/4 B) 1/10 C) 7/15 D) 8/15 E) 2/13
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)*4=7/15   Therefore, Remaining work =(1-(7/15))=8/15   Option 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 :