Some children board a school bus.
At Bus Stop A,
25 of them alight
and 3 children board.
At Bus Stop B,
25 of the children alight
and 7 board.
If there are 16 children on the bus now,
how many children are on the bus at first?
|
Number of children |
Before |
5 u |
|
Change 1 At Bus Stop A |
- 2 u + 3 |
|
After 1 |
3 u + 3 |
5 p |
Change 2 At Bus Stop B |
|
- 2 p + 7 |
After 2 |
|
16 |
Working backwards.
Number of children in the end = 16
5 p - 2 p = 16 - 7
3 p = 9
1 p = 9 ÷ 3 = 3
5 p = 5 x 3
5 p = 15
3 u + 3 = 5 p
3 u + 3 = 15
3 u = 15 - 3
3 u = 12
1 u = 12 ÷ 3 = 4
Total number of children at first
= 5 u
= 5 x 4
= 20
Answer(s): 20