When the injected water of pipe A is 30T, the injected water of pipe C is V-30.

When the water injected into the second pipe is 40T, the water injected into the third pipe is V-40.

Because the water injection rate of B per minute is 1.5 times that of A, and the time for A to inject 30T is equal to that for B to inject 45T.

So, it can be seen that:

(V - 30) / (V - 40) = 45 / 40

40(V - 30) = 45(V - 40)

5V = 600.

V = 120m3