Some pupils board a school bus.
At Bus Stop A,
57 of them alight
and 2 pupils board.
At Bus Stop B,
15 of the pupils alight
and 5 board.
If there are 13 pupils on the bus now,
how many pupils are on the bus at first?
|
Number of pupils |
Before |
7 u |
|
Change 1 At Bus Stop A |
- 5 u + 2 |
|
After 1 |
2 u + 2 |
5 p |
Change 2 At Bus Stop B |
|
- 1 p + 5 |
After 2 |
|
13 |
Working backwards.
Number of pupils in the end = 13
5 p - 1 p = 13 - 5
4 p = 8
1 p = 8 ÷ 4 = 2
5 p = 5 x 2
5 p = 10
2 u + 2 = 5 p
2 u + 2 = 10
2 u = 10 - 2
2 u = 8
1 u = 8 ÷ 2 = 4
Total number of pupils at first
= 7 u
= 7 x 4
= 28
Answer(s): 28