9 containers and 8 pails can hold 105.7 litres of water.
1 container and 1 pail can hold 12.2 litres of water.

1. How many litres of water can 1 container hold?
2. How many litres of water can 1 pail hold?
3. How many litres of water can 7 pails hold?
4. How many litres of water can 8 pails and 9 containers?

(a)
9 containers + 8 pails = 105.7 --- (1)
1 container + 1 pail = 12.2 --- (2)

(2) x 8
1 container + 1 pail = 12.2
8 containers + 8 pails = 12.2 x 8
8 containers + 8 pails = 97.6 --- (3)

(1) - (3)
(9 containers + 8 pails) - (8 containers + 8 pails) = 105.7 - 97.6
9 containers + 8 pails - 8 containers - 8 pails = 8.1
9 containers - 8 containers + 8 pails - 8 pails = 8.1

1 container = 8.1

Volume of 1 container = 8.1 ℓ

(b)
Substitute 1 container = 8.1 into (2).
1 container + 1 pail = 12.2
8.1 + 1 pail = 12.2

1 pail = 12.2 - 8.1 = 4.1

Volume of 1 pail = 4.1 ℓ

(c)
Volume of 7 pails
= 7 x 4.1
= 28.7 ℓ

(d)
Volume of 8 pails and 9 containers
= 8 x 4.1 + 9 x 8.1
= 32.8 + 72.9
= 105.7 ℓ

Answer(s): (a) 8.1 ℓ; (b) 4.1 ℓ; (c) 28.7 ℓ; (d) 105.7 ℓ