Arithmetic Aptitude :: Time and Work
8. A and B can together finish a work in 30 days. They worked together for 20 days and then B left. After another 20 days, A finished the remaining work. In how many days A alone can finish the job ?
(A + B)'s 1 day's work = 1/30
so (A&B) 20 days work = (20*1/30) = 2/3
so left work = (1?2/3)=1/3
1/3 work is done by A = 20 days.
So whole work will be done by A = (20 x 3) = 60 days.