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

	Scenario 1		Scenario 2
Container type	Container F	Container G	Container F	Container G
Volume of the container	3 u	7 u - 5	6 p	2 p x 5 = 10 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)
7 u - 5 = 10 p
7 u = 10 p + 5 --- (2)

Make u the same.

(1) x 7
21 u = 42 p --- (3)

(2) x 3
21 u = 30 p + 15 --- (4)

(3) = (4)
42 p = 30 p + 15
42 p - 30 p = 15
12 p = 15
1 p = 15 ÷ 12 = 1.25

Volume of Container G
= 10 p
= 10 x 1.25
= 12.5 ℓ

Answer(s): 12.5 ℓ