Some pupils board a school bus.
At Bus Stop A,
13 of them alight
and 10 pupils board.
At Bus Stop B,
58 of the pupils alight
and 3 board.
If there are 12 pupils on the bus now,
how many pupils are on the bus at first?
|
Number of pupils |
Before |
3 u |
|
Change 1 At Bus Stop A |
- 1 u + 10 |
|
After 1 |
2 u + 10 |
8 p |
Change 2 At Bus Stop B |
|
- 5 p + 3 |
After 2 |
|
12 |
Working backwards.
Number of pupils in the end = 12
8 p - 5 p = 12 - 3
3 p = 9
1 p = 9 ÷ 3 = 3
8 p = 8 x 3
8 p = 24
2 u + 10 = 8 p
2 u + 10 = 24
2 u = 24 - 10
2 u = 14
1 u = 14 ÷ 2 = 7
Total number of pupils at first
= 3 u
= 3 x 7
= 21
Answer(s): 21