130. A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?

✅ The correct answer is option C.
A’s 1 hour’s work =
1
;

4

(B + C)’s 1 hour’s work =
1
;

3

(A + C)’s 1 hour’s work =
1
.

2

(A + B + C)’s 1 hour’s work =

1
+
1

=
7
.

4
3
12

B’s 1 hour’s work =

7
–
1

=
1
.

12
2
12

B alone will take 12 hours to do the work.