The total mass of 2 boxes and 3 tanks was 11.2 kg.
The total mass of 5 boxes and 5 tanks was 21 kg.
- What is the mass of 1 box and 1 tank?
- What is the mass of 9 tanks?
- How much less is the mass of 1 tank than 1 box?
(a)
2 boxes + 3 tanks = 11.2 --- (1)
5 boxes + 5 tanks = 21 --- (2)
(2)
÷ 5 1 box + 1 tank = 4.2 --- (3)
Mass of 1 box and 1 tank = 4.2 kg
(b)
(3) x 2
2 boxes + 2 tanks = 2 x 4.2
2 boxes + 2 tanks = 8.4 --- (4)
(1) - (4)
(2 boxes + 3 tanks) - (2 boxes + 2 tanks) = 11.2 - 8.4
2 boxes - 2 boxes + 3 tanks - 2 tanks = 2.8
1 tank = 2.8
9 tanks = 2.8 x 9 = 25.2
Mass of 9 tanks = 25.2 kg
(c)
Substitute 1 tank = 2.8 into (3).
1 box + 1 tank = 4.2
1 box + 2.8 = 4.2
1 box = 4.2 - 2.8 = 1.4
Mass of 1 box = 1.4 kg
Mass of 1 box less than 1 tank
= 2.8 - 1.4
= 1.4 kg
Answer(s): (a) 4.2 kg; (b) 25.2 kg; (c) 1.4 kg