A can do a work in 15 days and B in 20 days. If they work on it together for 2 days, then the fraction of the work that is left is :	Choose the correct choice from the following answers
A) 23/20	B) 5	C) 23/30	D) 23/12	E) 2
Ans is:C   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 2 day's work =(7/60*2)=7/30   Therefore, Remaining work =(1-7/30)=23/30. Ans: 23/30
<result>C</result>
A can do a work in 15 days and B in 20 days. If they work on it together for 2 days, then the fraction of the work that is left is :