A and B can together finish a work 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 work? Choose the correct answer:
A) 10 days.	B) 30 days.	C) 60 days.	D) 20 days.	E) 50 days.
(A + B)'s 20 day's work =(1/30 x 20)	=2/3	.   Remaining work =(1 -2/3)=1/3.   Now,	1/3	work is done by A in 20 days.   Therefore, the whole work will be done by A in (20 x 3) = 60 days.   Answer: Option 60 days.
<result>C</result>
A and B can together finish a work 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 work?