The total mass of 4 boxes and 5 tanks was 21.6 kg.
The total mass of 6 boxes and 6 tanks was 28.2 kg.
- What is the mass of 1 box and 1 tank?
- What is the mass of 7 tanks?
- How much less is the mass of 1 tank than 1 box?
(a)
4 boxes + 5 tanks = 21.6 --- (1)
6 boxes + 6 tanks = 28.2 --- (2)
(2)
÷ 6 1 box + 1 tank = 4.7 --- (3)
Mass of 1 box and 1 tank = 4.7 kg
(b)
(3) x 4
4 boxes + 4 tanks = 4 x 4.7
4 boxes + 4 tanks = 18.8 --- (4)
(1) - (4)
(4 boxes + 5 tanks) - (4 boxes + 4 tanks) = 21.6 - 18.8
4 boxes - 4 boxes + 5 tanks - 4 tanks = 2.8
1 tank = 2.8
7 tanks = 2.8 x 7 = 19.6
Mass of 7 tanks = 19.6 kg
(c)
Substitute 1 tank = 2.8 into (3).
1 box + 1 tank = 4.7
1 box + 2.8 = 4.7
1 box = 4.7 - 2.8 = 1.9
Mass of 1 box = 1.9 kg
Mass of 1 box less than 1 tank
= 2.8 - 1.9
= 0.9 kg
Answer(s): (a) 4.7 kg; (b) 19.6 kg; (c) 0.9 kg