4 containers and 3 tanks can hold 23.3 litres of water.
1 container and 1 tank can hold 6.5 litres of water.

1. How many litres of water can 1 container hold?
2. How many litres of water can 1 tank hold?
3. How many litres of water can 4 tanks hold?
4. How many litres of water can 6 tanks and 4 containers?

(a)
4 containers + 3 tanks = 23.3 --- (1)
1 container + 1 tank = 6.5 --- (2)

(2) x 3
1 container + 1 tank = 6.5
3 containers + 3 tanks = 6.5 x 3
3 containers + 3 tanks = 19.5 --- (3)

(1) - (3)
(4 containers + 3 tanks) - (3 containers + 3 tanks) = 23.3 - 19.5
4 containers + 3 tanks - 3 containers - 3 tanks = 3.8
4 containers - 3 containers + 3 tanks - 3 tanks = 3.8

1 container = 3.8

Volume of 1 container = 3.8 ℓ

(b)
Substitute 1 container = 3.8 into (2).
1 container + 1 tank = 6.5
3.8 + 1 tank = 6.5

1 tank = 6.5 - 3.8 = 2.7

Volume of 1 tank = 2.7 ℓ

(c)
Volume of 4 tanks
= 4 x 2.7
= 10.8 ℓ

(d)
Volume of 6 tanks and 4 containers
= 6 x 2.7 + 4 x 3.8
= 16.2 + 15.2
= 31.4 ℓ

Answer(s): (a) 3.8 ℓ; (b) 2.7 ℓ; (c) 10.8 ℓ; (d) 31.4 ℓ