9 tanks and 8 pails can hold 60.7 litres of water.
1 tank and 1 pail can hold 6.9 litres of water.
- How many litres of water can 1 tank hold?
- How many litres of water can 1 pail hold?
- How many litres of water can 9 pails hold?
- How many litres of water can 7 pails and 9 tanks?
(a)
9 tanks + 8 pails = 60.7 --- (1)
1 tank + 1 pail = 6.9 --- (2)
(2) x 8
1 tank + 1 pail = 6.9
8 tanks + 8 pails = 6.9 x 8
8 tanks + 8 pails = 55.2 --- (3)
(1) - (3)
(9 tanks + 8 pails) - (8 tanks + 8 pails) = 60.7 - 55.2
9 tanks + 8 pails - 8 tanks - 8 pails = 5.5
9 tanks - 8 tanks + 8 pails - 8 pails = 5.5
1 tank = 5.5
Volume of 1 tank = 5.5 ℓ
(b)
Substitute 1 tank = 5.5 into (2).
1 tank + 1 pail = 6.9
5.5 + 1 pail = 6.9
1 pail = 6.9 - 5.5 = 1.4
Volume of 1 pail = 1.4 ℓ
(c)
Volume of 9 pails
= 9 x 1.4
= 12.6 ℓ
(d)
Volume of 7 pails and 9 tanks
= 7 x 1.4 + 9 x 5.5
= 9.8 + 49.5
= 59.3 ℓ
Answer(s): (a) 5.5 ℓ; (b) 1.4 ℓ; (c) 12.6 ℓ; (d) 59.3 ℓ