4 tanks and 3 containers can hold 41.7 litres of water.
1 tank and 1 container can hold 11.1 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 5 containers hold?
4. How many litres of water can 4 containers and 4 tanks?

(a)
4 tanks + 3 containers = 41.7 --- (1)
1 tank + 1 container = 11.1 --- (2)

(2) x 3
1 tank + 1 container = 11.1
3 tanks + 3 containers = 11.1 x 3
3 tanks + 3 containers = 33.3 --- (3)

(1) - (3)
(4 tanks + 3 containers) - (3 tanks + 3 containers) = 41.7 - 33.3
4 tanks + 3 containers - 3 tanks - 3 containers = 8.4
4 tanks - 3 tanks + 3 containers - 3 containers = 8.4

1 tank = 8.4

Volume of 1 tank = 8.4 ℓ

(b)
Substitute 1 tank = 8.4 into (2).
1 tank + 1 container = 11.1
8.4 + 1 container = 11.1

1 container = 11.1 - 8.4 = 2.7

Volume of 1 container = 2.7 ℓ

(c)
Volume of 5 containers
= 5 x 2.7
= 13.5 ℓ

(d)
Volume of 4 containers and 4 tanks
= 4 x 2.7 + 4 x 8.4
= 10.8 + 33.6
= 44.4 ℓ

Answer(s): (a) 8.4 ℓ; (b) 2.7 ℓ; (c) 13.5 ℓ; (d) 44.4 ℓ