9 containers and 8 pails can hold 85.7 litres of water.
1 container and 1 pail can hold 9.7 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 3 pails hold?
4. How many litres of water can 3 pails and 9 containers?

(a)
9 containers + 8 pails = 85.7 --- (1)
1 container + 1 pail = 9.7 --- (2)

(2) x 8
1 container + 1 pail = 9.7
8 containers + 8 pails = 9.7 x 8
8 containers + 8 pails = 77.6 --- (3)

(1) - (3)
(9 containers + 8 pails) - (8 containers + 8 pails) = 85.7 - 77.6
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 = 9.7
8.1 + 1 pail = 9.7

1 pail = 9.7 - 8.1 = 1.6

Volume of 1 pail = 1.6 ℓ

(c)
Volume of 3 pails
= 3 x 1.6
= 4.8 ℓ

(d)
Volume of 3 pails and 9 containers
= 3 x 1.6 + 9 x 8.1
= 4.8 + 72.9
= 77.7 ℓ

Answer(s): (a) 8.1 ℓ; (b) 1.6 ℓ; (c) 4.8 ℓ; (d) 77.7 ℓ