5 tanks and 4 containers can hold 47.8 litres of water.
1 tank and 1 container can hold 10.3 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 5 tanks?

(a)
5 tanks + 4 containers = 47.8 --- (1)
1 tank + 1 container = 10.3 --- (2)

(2) x 4
1 tank + 1 container = 10.3
4 tanks + 4 containers = 10.3 x 4
4 tanks + 4 containers = 41.2 --- (3)

(1) - (3)
(5 tanks + 4 containers) - (4 tanks + 4 containers) = 47.8 - 41.2
5 tanks + 4 containers - 4 tanks - 4 containers = 6.6
5 tanks - 4 tanks + 4 containers - 4 containers = 6.6

1 tank = 6.6

Volume of 1 tank = 6.6 ℓ

(b)
Substitute 1 tank = 6.6 into (2).
1 tank + 1 container = 10.3
6.6 + 1 container = 10.3

1 container = 10.3 - 6.6 = 3.7

Volume of 1 container = 3.7 ℓ

(c)
Volume of 9 containers
= 9 x 3.7
= 33.3 ℓ

(d)
Volume of 5 containers and 5 tanks
= 5 x 3.7 + 5 x 6.6
= 18.5 + 33
= 51.5 ℓ

Answer(s): (a) 6.6 ℓ; (b) 3.7 ℓ; (c) 33.3 ℓ; (d) 51.5 ℓ