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

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

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

4 u = 3 p --- (1)
7 u - 6 = 4 p
7 u = 4 p + 6 --- (2)

Make u the same.

(1) x 7
28 u = 21 p --- (3)

(2) x 4
28 u = 16 p + 24 --- (4)

(3) = (4)
21 p = 16 p + 24
21 p - 16 p = 24
5 p = 24
1 p = 24 ÷ 5 = 4.8

Volume of Tank V
= 4 p
= 4 x 4.8
= 19.2 ℓ

Answer(s): 19.2 ℓ