Correct Answer: Option D
(A + B)'s 20 day's work =(1/30 x20) = 2/3
Remaining work = (1 -2/3) = 2/3.
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.
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