6 pails and 5 tanks can hold 33.8 litres of water.
1 pail and 1 tank can hold 6.2 litres of water.

1. How many litres of water can 1 pail hold?
2. How many litres of water can 1 tank hold?
3. How many litres of water can 8 tanks hold?
4. How many litres of water can 6 tanks and 6 pails?

(a)
6 pails + 5 tanks = 33.8 --- (1)
1 pail + 1 tank = 6.2 --- (2)

(2) x 5
1 pail + 1 tank = 6.2
5 pails + 5 tanks = 6.2 x 5
5 pails + 5 tanks = 31 --- (3)

(1) - (3)
(6 pails + 5 tanks) - (5 pails + 5 tanks) = 33.8 - 31
6 pails + 5 tanks - 5 pails - 5 tanks = 2.8
6 pails - 5 pails + 5 tanks - 5 tanks = 2.8

1 pail = 2.8

Volume of 1 pail = 2.8 ℓ

(b)
Substitute 1 pail = 2.8 into (2).
1 pail + 1 tank = 6.2
2.8 + 1 tank = 6.2

1 tank = 6.2 - 2.8 = 3.4

Volume of 1 tank = 3.4 ℓ

(c)
Volume of 8 tanks
= 8 x 3.4
= 27.2 ℓ

(d)
Volume of 6 tanks and 6 pails
= 6 x 3.4 + 6 x 2.8
= 20.4 + 16.8
= 37.2 ℓ

Answer(s): (a) 2.8 ℓ; (b) 3.4 ℓ; (c) 27.2 ℓ; (d) 37.2 ℓ