Some pupils board a school bus.
At Bus Stop A,
13 of them alight
and 2 pupils board.
At Bus Stop B,
14 of the pupils alight
and 2 board.
If there are 14 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 + 2 |
|
After 1 |
2 u + 2 |
4 p |
Change 2 At Bus Stop B |
|
- 1 p + 2 |
After 2 |
|
14 |
Working backwards.
Number of pupils in the end = 14
4 p - 1 p = 14 - 2
3 p = 12
1 p = 12 ÷ 3 = 4
4 p = 4 x 4
4 p = 16
2 u + 2 = 4 p
2 u + 2 = 16
2 u = 16 - 2
2 u = 14
1 u = 14 ÷ 2 = 7
Total number of pupils at first
= 3 u
= 3 x 7
= 21
Answer(s): 21