Answer with Explanation:
(B + C)'s 1 day's work = 1/9 + 1/12 = 7/36 .
Work done by B and C in 3 days = (7/36 x 3) = 7/12 .
Remaining work = (1 - 7/12) = 5/12 .
Now,1/24 work is done by A in 1 day.
So,5/12 work is done by A in (24 x 5/12) = 10 Days.
(B + C)'s 1 day's work = 1/9 + 1/12 = 7/36 .
Work done by B and C in 3 days = (7/36 x 3) = 7/12 .
Remaining work = (1 - 7/12) = 5/12 .
Now,1/24 work is done by A in 1 day.
So,5/12 work is done by A in (24 x 5/12) = 10 Days.