Some pupils board a school bus.
At Bus Stop A,
13 of them alight
and 11 pupils board.
At Bus Stop B,
35 of the pupils alight
and 4 board.
If there are 10 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 + 11 |
|
After 1 |
2 u + 11 |
5 p |
Change 2 At Bus Stop B |
|
- 3 p + 4 |
After 2 |
|
10 |
Working backwards.
Number of pupils in the end = 10
5 p - 3 p = 10 - 4
2 p = 6
1 p = 6 ÷ 2 = 3
5 p = 5 x 3
5 p = 15
2 u + 11 = 5 p
2 u + 11 = 15
2 u = 15 - 11
2 u = 4
1 u = 4 ÷ 2 = 2
Total number of pupils at first
= 3 u
= 3 x 2
= 6
Answer(s): 6