3 tanks and 2 pails can hold 35.7 litres of water.
1 tank and 1 pail can hold 13.4 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 5 pails hold?
4. How many litres of water can 3 pails and 3 tanks?

(a)
3 tanks + 2 pails = 35.7 --- (1)
1 tank + 1 pail = 13.4 --- (2)

(2) x 2
1 tank + 1 pail = 13.4
2 tanks + 2 pails = 13.4 x 2
2 tanks + 2 pails = 26.8 --- (3)

(1) - (3)
(3 tanks + 2 pails) - (2 tanks + 2 pails) = 35.7 - 26.8
3 tanks + 2 pails - 2 tanks - 2 pails = 8.9
3 tanks - 2 tanks + 2 pails - 2 pails = 8.9

1 tank = 8.9

Volume of 1 tank = 8.9 ℓ

(b)
Substitute 1 tank = 8.9 into (2).
1 tank + 1 pail = 13.4
8.9 + 1 pail = 13.4

1 pail = 13.4 - 8.9 = 4.5

Volume of 1 pail = 4.5 ℓ

(c)
Volume of 5 pails
= 5 x 4.5
= 22.5 ℓ

(d)
Volume of 3 pails and 3 tanks
= 3 x 4.5 + 3 x 8.9
= 13.5 + 26.7
= 40.2 ℓ

Answer(s): (a) 8.9 ℓ; (b) 4.5 ℓ; (c) 22.5 ℓ; (d) 40.2 ℓ