Ethan has 2 containers. Container J and Container K are of different capacities. If Container J is filled by a tap at a rate of 3 litres per minute and Container K is filled by a tap at a rate of 5 litres per minute, when Container J is completely filled, 7 litres of water flowed out from Container K. If Container J is filled by a tap at a rate of 6 litres per minute and Container K is filled by a tap at a rate of 2 litres per minute, when Container J is completely filled, Container K is only one-quarter-filled. What is the capacity of Container K? Express your answer in litres.

	Scenario 1		Scenario 2
Container type	Container J	Container K	Container J	Container K
Volume of the container	3 u	5 u - 7	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.

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

Make u the same.

(1) x 5
15 u = 30 p --- (3)

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

(3) = (4)
30 p = 24 p + 21
30 p - 24 p = 21
6 p = 21
1 p = 21 ÷ 6 = 3.5

Volume of Container K
= 8 p
= 8 x 3.5
= 28 ℓ

Answer(s): 28 ℓ