A and B together can do a piece of work in 20days. A having worked for 10days, B finishes the remaining work alone in 30days. In how many days shall B finish the whole work?	Select the correct option
A) 25  B) 40  C) 50  D) 30  E) 60
Let A's 1day work = x   40's 1day work = y   x+y = 1/20   10x+30y = 1   x = 1/40   y = 1/40   40's 1 day work = 1/40   40 alone can finish the job in 40 days   Answer is 40
<result>B</result>
A and B together can do a piece of work in 20days. A having worked for 10days, B finishes the remaining work alone in 30days. In how many days shall B finish the whole work?