A) 60

B) 45

C) 40

D) 30

Using Flip rule:

A and B complete work in = 15 days

One day’s work of (A + B) = 1/15

B complete the work in = 20 days;

One day’s work of B = 1/20

Then, A’s one day’s work

=1/15−1/20 = ( 6-5)/60= 1/60

Thus, A can complete the work in =** 60 days.**

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