6 tanks and 5 containers can hold 58.3 litres of water.
1 tank and 1 container can hold 10.5 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 4 containers hold?
4. How many litres of water can 8 containers and 6 tanks?

(a)
6 tanks + 5 containers = 58.3 --- (1)
1 tank + 1 container = 10.5 --- (2)

(2) x 5
1 tank + 1 container = 10.5
5 tanks + 5 containers = 10.5 x 5
5 tanks + 5 containers = 52.5 --- (3)

(1) - (3)
(6 tanks + 5 containers) - (5 tanks + 5 containers) = 58.3 - 52.5
6 tanks + 5 containers - 5 tanks - 5 containers = 5.8
6 tanks - 5 tanks + 5 containers - 5 containers = 5.8

1 tank = 5.8

Volume of 1 tank = 5.8 ℓ

(b)
Substitute 1 tank = 5.8 into (2).
1 tank + 1 container = 10.5
5.8 + 1 container = 10.5

1 container = 10.5 - 5.8 = 4.7

Volume of 1 container = 4.7 ℓ

(c)
Volume of 4 containers
= 4 x 4.7
= 18.8 ℓ

(d)
Volume of 8 containers and 6 tanks
= 8 x 4.7 + 6 x 5.8
= 37.6 + 34.8
= 72.4 ℓ

Answer(s): (a) 5.8 ℓ; (b) 4.7 ℓ; (c) 18.8 ℓ; (d) 72.4 ℓ