Zoe has 2 tanks. Tank B and Tank C are of different capacities. If Tank B is filled by a tap at a rate of 4 litres per minute and Tank C is filled by a tap at a rate of 6 litres per minute, when Tank B is completely filled, 5 litres of water flowed out from Tank C. If Tank B is filled by a tap at a rate of 6 litres per minute and Tank C is filled by a tap at a rate of 2 litres per minute, when Tank B is completely filled, Tank C is only one-quarter-filled. What is the capacity of Tank C? Express your answer in litres.

	Scenario 1		Scenario 2
Tank type	Tank B	Tank C	Tank B	Tank C
Volume of the tank	4 u	6 u - 5	6 p	2 p x 4 = 8 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)
6 u - 5 = 8 p
6 u = 8 p + 5 --- (2)

Make u the same.

(1) x 3
12 u = 18 p --- (3)

(2) x 2
12 u = 16 p + 10 --- (4)

(3) = (4)
18 p = 16 p + 10
18 p - 16 p = 10
2 p = 10
1 p = 10 ÷ 2 = 5

Volume of Tank C
= 8 p
= 8 x 5
= 40 ℓ

Answer(s): 40 ℓ