Harper has 2 containers. Container E and Container F are of different capacities. If Container E is filled by a tap at a rate of 4 litres per minute and Container F is filled by a tap at a rate of 7 litres per minute, when Container E is completely filled, 6 litres of water flowed out from Container F. If Container E is filled by a tap at a rate of 6 litres per minute and Container F is filled by a tap at a rate of 5 litres per minute, when Container E is completely filled, Container F is only half-filled. What is the capacity of Container F? Express your answer in litres.

	Scenario 1		Scenario 2
Container type	Container E	Container F	Container E	Container F
Volume of the container	4 u	7 u - 6	6 p	5 p x 2 = 10 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 = 10 p
7 u = 10 p + 6 --- (2)

Make u the same.

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

(2) x 4
28 u = 40 p + 24 --- (4)

(3) = (4)
42 p = 40 p + 24
42 p - 40 p = 24
2 p = 24
1 p = 24 ÷ 2 = 12

Volume of Container F
= 10 p
= 10 x 12
= 120 ℓ

Answer(s): 120 ℓ