Jackson has 2 tanks. Tank A and Tank B are of different capacities. If Tank A is filled by a tap at a rate of 4 litres per minute and Tank B is filled by a tap at a rate of 7 litres per minute, when Tank A is completely filled, 6 litres of water flowed out from Tank B. If Tank A is filled by a tap at a rate of 6 litres per minute and Tank B is filled by a tap at a rate of 3 litres per minute, when Tank A is completely filled, Tank B is only one-third-filled. What is the capacity of Tank B? Express your answer in litres.

	Scenario 1		Scenario 2
Tank type	Tank A	Tank B	Tank A	Tank B
Volume of the tank	4 u	7 u - 6	6 p	3 p x 3 = 9 p

Let 1 u be the time taken for Scenario 1.
Let 1 p be the time taken for Scenario 2.

4 u = 6 p --- (1)
7 u - 6 = 9 p
7 u = 9 p + 6 --- (2)

Make u the same.

(1) x 7
28 u = 42 p --- (3)

(2) x 4
28 u = 36 p + 24 --- (4)

(3) = (4)
42 p = 36 p + 24
42 p - 36 p = 24
6 p = 24
1 p = 24 ÷ 6 = 4

Volume of Tank B
= 9 p
= 9 x 4
= 36 ℓ

Answer(s): 36 ℓ