A and B can together finish a work in 30 days. They worked together for 20 days and then B left after 20 days. A finished the worked. In how many days A alone can finish the work?
A and B can together finish a work in 30 days. They worked together for 20 days and then B left after 20 days. A finished the worked. In how many days A alone can finish the work?
Explanation
Amount of work done by A and B in 1 day = 1/30
Amount of work done by A and B in 20 days = 20 × (1/30) = 20/30 = 2/3
Remaining work – 1 – 2/3 = 1/3
A completes 1/3 work in 20 days
Amount of work A can do in 1 day = (1/3)/20 = 1/60
=> A can complete the work in 60 days