Henry has 2 containers. Container F and Container G are of different capacities. If Container F is filled by a tap at a rate of 4 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, 6 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 4 litres per minute, when Container F is completely filled, Container G is only half-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	4 u	7 u - 6	6 p	4 p x 2 = 8 p

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

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

Make u the same.

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

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

(3) = (4)
42 p = 32 p + 24
42 p - 32 p = 24
10 p = 24
1 p = 24 ÷ 10 = 2.4

Volume of Container G
= 8 p
= 8 x 2.4
= 19.2 ℓ

Answer(s): 19.2 ℓ