Aaron has 2 tanks. Tank M and Tank N are of different capacities. If Tank M is filled by a tap at a rate of 3 litres per minute and Tank N is filled by a tap at a rate of 7 litres per minute, when Tank M is completely filled, 8 litres of water flowed out from Tank N. If Tank M is filled by a tap at a rate of 4 litres per minute and Tank N is filled by a tap at a rate of 2 litres per minute, when Tank M is completely filled, Tank N is only one-third-filled. What is the capacity of Tank N? Express your answer in litres.

	Scenario 1		Scenario 2
Tank type	Tank M	Tank N	Tank M	Tank N
Volume of the tank	3 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.

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

Make u the same.

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

(2) x 3
21 u = 18 p + 24 --- (4)

(3) = (4)
28 p = 18 p + 24
28 p - 18 p = 24
10 p = 24
1 p = 24 ÷ 10 = 2.4

Volume of Tank N
= 6 p
= 6 x 2.4
= 14.4 ℓ

Answer(s): 14.4 ℓ