The total mass of 3 tanks and 4 boxes was 20.9 kg.
The total mass of 5 tanks and 5 boxes was 28 kg.
- What is the mass of 1 tank and 1 box?
- What is the mass of 7 boxes?
- How much less is the mass of 1 box than 1 tank?
(a)
3 tanks + 4 boxes = 20.9 --- (1)
5 tanks + 5 boxes = 28 --- (2)
(2)
÷ 5 1 tank + 1 box = 5.6 --- (3)
Mass of 1 tank and 1 box = 5.6 kg
(b)
(3) x 3
3 tanks + 3 boxes = 3 x 5.6
3 tanks + 3 boxes = 16.8 --- (4)
(1) - (4)
(3 tanks + 4 tanks) - (3 tanks + 3 tanks) = 20.9 - 16.8
3 tanks - 3 tanks + 4 boxes - 3 boxes = 4.1
1 box = 4.1
7 boxes = 4.1 x 7 = 28.7
Mass of 7 boxes = 28.7 kg
(c)
Substitute 1 box = 4.1 into (3).
1 tank + 1 box = 5.6
1 tank + 4.1 = 5.6
1 tank = 5.6 - 4.1 = 1.5
Mass of 1 tank = 1.5 kg
Mass of 1 tank less than 1 box
= 4.1 - 1.5
= 2.6 kg
Answer(s): (a) 5.6 kg; (b) 28.7 kg; (c) 2.6 kg