9 tanks and 8 containers can hold 48.6 litres of water.
1 tank and 1 container can hold 5.6 litres of water.

1. How many litres of water can 1 tank hold?
2. How many litres of water can 1 container hold?
3. How many litres of water can 9 containers hold?
4. How many litres of water can 5 containers and 9 tanks?

(a)
9 tanks + 8 containers = 48.6 --- (1)
1 tank + 1 container = 5.6 --- (2)

(2) x 8
1 tank + 1 container = 5.6
8 tanks + 8 containers = 5.6 x 8
8 tanks + 8 containers = 44.8 --- (3)

(1) - (3)
(9 tanks + 8 containers) - (8 tanks + 8 containers) = 48.6 - 44.8
9 tanks + 8 containers - 8 tanks - 8 containers = 3.8
9 tanks - 8 tanks + 8 containers - 8 containers = 3.8

1 tank = 3.8

Volume of 1 tank = 3.8 ℓ

(b)
Substitute 1 tank = 3.8 into (2).
1 tank + 1 container = 5.6
3.8 + 1 container = 5.6

1 container = 5.6 - 3.8 = 1.8

Volume of 1 container = 1.8 ℓ

(c)
Volume of 9 containers
= 9 x 1.8
= 16.2 ℓ

(d)
Volume of 5 containers and 9 tanks
= 5 x 1.8 + 9 x 3.8
= 9 + 34.2
= 43.2 ℓ

Answer(s): (a) 3.8 ℓ; (b) 1.8 ℓ; (c) 16.2 ℓ; (d) 43.2 ℓ