9 tanks and 8 pails can hold 92.9 litres of water.
1 tank and 1 pail can hold 10.8 litres of water.

1. How many litres of water can 1 tank 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 6 pails and 9 tanks?

(a)
9 tanks + 8 pails = 92.9 --- (1)
1 tank + 1 pail = 10.8 --- (2)

(2) x 8
1 tank + 1 pail = 10.8
8 tanks + 8 pails = 10.8 x 8
8 tanks + 8 pails = 86.4 --- (3)

(1) - (3)
(9 tanks + 8 pails) - (8 tanks + 8 pails) = 92.9 - 86.4
9 tanks + 8 pails - 8 tanks - 8 pails = 6.5
9 tanks - 8 tanks + 8 pails - 8 pails = 6.5

1 tank = 6.5

Volume of 1 tank = 6.5 ℓ

(b)
Substitute 1 tank = 6.5 into (2).
1 tank + 1 pail = 10.8
6.5 + 1 pail = 10.8

1 pail = 10.8 - 6.5 = 4.3

Volume of 1 pail = 4.3 ℓ

(c)
Volume of 3 pails
= 3 x 4.3
= 12.9 ℓ

(d)
Volume of 6 pails and 9 tanks
= 6 x 4.3 + 9 x 6.5
= 25.8 + 58.5
= 84.3 ℓ

Answer(s): (a) 6.5 ℓ; (b) 4.3 ℓ; (c) 12.9 ℓ; (d) 84.3 ℓ