The total mass of 4 boxes and 5 tanks was 31.8 kg.
The total mass of 6 boxes and 6 tanks was 42 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)
4 boxes + 5 tanks = 31.8 --- (1)
6 boxes + 6 tanks = 42 --- (2)
(2)
÷ 6 1 box + 1 tank = 7 --- (3)
Mass of 1 box and 1 tank = 7 kg
(b)
(3) x 4
4 boxes + 4 tanks = 4 x 7
4 boxes + 4 tanks = 28 --- (4)
(1) - (4)
(4 boxes + 5 tanks) - (4 boxes + 4 tanks) = 31.8 - 28
4 boxes - 4 boxes + 5 tanks - 4 tanks = 3.8
1 tank = 3.8
9 tanks = 3.8 x 9 = 34.2
Mass of 9 tanks = 34.2 kg
(c)
Substitute 1 tank = 3.8 into (3).
1 box + 1 tank = 7
1 box + 3.8 = 7
1 box = 7 - 3.8 = 3.2
Mass of 1 box = 3.2 kg
Mass of 1 box less than 1 tank
= 3.8 - 3.2
= 0.6 kg
Answer(s): (a) 7 kg; (b) 34.2 kg; (c) 0.6 kg