Some pupils board a school bus.
At Bus Stop A,
49 of them alight
and 6 pupils board.
At Bus Stop B,
13 of the pupils alight
and 6 board.
If there are 20 pupils on the bus now,
how many pupils are on the bus at first?
|
Number of pupils |
Before |
9 u |
|
Change 1 At Bus Stop A |
- 4 u + 6 |
|
After 1 |
5 u + 6 |
3 p |
Change 2 At Bus Stop B |
|
- 1 p + 6 |
After 2 |
|
20 |
Working backwards.
Number of pupils in the end = 20
3 p - 1 p = 20 - 6
2 p = 14
1 p = 14 ÷ 2 = 7
3 p = 3 x 7
3 p = 21
5 u + 6 = 3 p
5 u + 6 = 21
5 u = 21 - 6
5 u = 15
1 u = 15 ÷ 5 = 3
Total number of pupils at first
= 9 u
= 9 x 3
= 27
Answer(s): 27