The total mass of 3 tanks and 4 boxes was 15.7 kg.
The total mass of 4 tanks and 4 boxes was 16.8 kg.
- What is the mass of 1 tank and 1 box?
- What is the mass of 9 boxes?
- How much less is the mass of 1 box than 1 tank?
(a)
3 tanks + 4 boxes = 15.7 --- (1)
4 tanks + 4 boxes = 16.8 --- (2)
(2)
÷ 4 1 tank + 1 box = 4.2 --- (3)
Mass of 1 tank and 1 box = 4.2 kg
(b)
(3) x 3
3 tanks + 3 boxes = 3 x 4.2
3 tanks + 3 boxes = 12.6 --- (4)
(1) - (4)
(3 tanks + 4 tanks) - (3 tanks + 3 tanks) = 15.7 - 12.6
3 tanks - 3 tanks + 4 boxes - 3 boxes = 3.1
1 box = 3.1
9 boxes = 3.1 x 9 = 27.9
Mass of 9 boxes = 27.9 kg
(c)
Substitute 1 box = 3.1 into (3).
1 tank + 1 box = 4.2
1 tank + 3.1 = 4.2
1 tank = 4.2 - 3.1 = 1.1
Mass of 1 tank = 1.1 kg
Mass of 1 tank less than 1 box
= 3.1 - 1.1
= 2 kg
Answer(s): (a) 4.2 kg; (b) 27.9 kg; (c) 2 kg