Q) 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?    

a) 40 days              b) 50 days               c) 54 days                     d) 60 days

Ans:

(A + B)’s 1 day’s work = 1/30

∴ work done by (A + B) in 20 days = 20/30 = 2/3

∴ Balance work = 1 – 2/3 = 1/3

Since A finished 1/3 work in 20 days (given)

∴ A can finish whole work in 20/(1/3) = 60 days

Hence, Answer is [D].

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