A and B can do a piece of work in 10 days. B and C can do it in 12 days. A and C can do it in 15 days. How long will A take to do it alone?

[A]20 days

[B]24 days

[C]30 days

[D]40 days

**24 days**

(A + B)’s 1 day’s work

(B + C)’s 1 day’s work

(C + A)’s 1 day’s work

On adding,

2(A + B + C)’s 1 day’s work

∴ (A + B + C)’s 1 day’s work

∴ A’s 1 day’s work

∴ A alone will complete the work in 24 days.

Hence option [B] is correct answer.