JOHN and ANDREW can finish John work 30 days if they work together. They worked together for 20 days and then ANDREW left. JOHN finished the remaining work in another 20 days. In how many days JOHN alone can finish the work? Answers:
A) 40
B) 50
C) 55
D) 58
E) 60
Amount of work done by JOHN and ANDR60W in 1 day = 1/30   Amount of work done by JOHN and ANDR60W in 20 days = 20 × (1/30) = 20/30 = 2/3   Remaining work – 1 – 2/3 = 1/3   JOHN completes 1/3 work in 20 days   Amount of work JOHN can do in 1 day = (1/3)/20 = 1/60   =&gt; JOHN can complete the work in 60 days   60
<result>E</result>
JOHN and ANDREW can finish John work 30 days if they work together. They worked together for 20 days and then ANDREW left. JOHN finished the remaining work in another 20 days. In how many days JOHN alone can finish the work?