The total mass of 3 boxes and 4 tanks was 12.4 kg.
The total mass of 5 boxes and 5 tanks was 17.5 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)
3 boxes + 4 tanks = 12.4 --- (1)
5 boxes + 5 tanks = 17.5 --- (2)
(2)
÷ 5 1 box + 1 tank = 3.5 --- (3)
Mass of 1 box and 1 tank = 3.5 kg
(b)
(3) x 3
3 boxes + 3 tanks = 3 x 3.5
3 boxes + 3 tanks = 10.5 --- (4)
(1) - (4)
(3 boxes + 4 tanks) - (3 boxes + 3 tanks) = 12.4 - 10.5
3 boxes - 3 boxes + 4 tanks - 3 tanks = 1.9
1 tank = 1.9
7 tanks = 1.9 x 7 = 13.3
Mass of 7 tanks = 13.3 kg
(c)
Substitute 1 tank = 1.9 into (3).
1 box + 1 tank = 3.5
1 box + 1.9 = 3.5
1 box = 3.5 - 1.9 = 1.6
Mass of 1 box = 1.6 kg
Mass of 1 box less than 1 tank
= 1.9 - 1.6
= 0.3 kg
Answer(s): (a) 3.5 kg; (b) 13.3 kg; (c) 0.3 kg