Some pupils board a school bus.
At Bus Stop A,
15 of them alight
and 4 pupils board.
At Bus Stop B,
57 of the pupils alight
and 3 board.
If there are 11 pupils on the bus now,
how many pupils are on the bus at first?
|
Number of pupils |
Before |
5 u |
|
Change 1 At Bus Stop A |
- 1 u + 4 |
|
After 1 |
4 u + 4 |
7 p |
Change 2 At Bus Stop B |
|
- 5 p + 3 |
After 2 |
|
11 |
Working backwards.
Number of pupils in the end = 11
7 p - 5 p = 11 - 3
2 p = 8
1 p = 8 ÷ 2 = 4
7 p = 7 x 4
7 p = 28
4 u + 4 = 7 p
4 u + 4 = 28
4 u = 28 - 4
4 u = 24
1 u = 24 ÷ 4 = 6
Total number of pupils at first
= 5 u
= 5 x 6
= 30
Answer(s): 30