P is able to do a piece of work in 15 days and Q can do the same work in 20 days. If they can work together for 4 days, what is the fraction of work left?
Q1. P is able to do a piece of work in 15 days and Q can do the same work in 20 days. If they can work together for 4 days, what is the fraction of work left?
Answer: Aug-15
Explanation: P and Q together complete 4×(1/15 + 1/20) = 7/15 of the work in 4 days, leaving 8/15 unfinished.