Tommy has 2 tanks. Tank V and Tank W are of different capacities. If Tank V is filled by a tap at a rate of 4 litres per minute and Tank W is filled by a tap at a rate of 7 litres per minute, when Tank V is completely filled, 8 litres of water flowed out from Tank W. If Tank V is filled by a tap at a rate of 4 litres per minute and Tank W is filled by a tap at a rate of 2 litres per minute, when Tank V is completely filled, Tank W is only one-third-filled. What is the capacity of Tank W? Express your answer in litres.

	Scenario 1		Scenario 2
Tank type	Tank V	Tank W	Tank V	Tank W
Volume of the tank	4 u	7 u - 8	4 p	2 p x 3 = 6 p

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

4 u = 4 p --- (1)
7 u - 8 = 6 p
7 u = 6 p + 8 --- (2)

Make u the same.

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

(2) x 4
28 u = 24 p + 32 --- (4)

(3) = (4)
28 p = 24 p + 32
28 p - 24 p = 32
4 p = 32
1 p = 32 ÷ 4 = 8

Volume of Tank W
= 6 p
= 6 x 8
= 48 ℓ

Answer(s): 48 ℓ