Some children board a school bus.
At Bus Stop A,
27 of them alight
and 10 children board.
At Bus Stop B,
35 of the children alight
and 7 board.
If there are 15 children on the bus now,
how many children are on the bus at first?
|
Number of children |
Before |
7 u |
|
Change 1 At Bus Stop A |
- 2 u + 10 |
|
After 1 |
5 u + 10 |
5 p |
Change 2 At Bus Stop B |
|
- 3 p + 7 |
After 2 |
|
15 |
Working backwards.
Number of children in the end = 15
5 p - 3 p = 15 - 7
2 p = 8
1 p = 8 ÷ 2 = 4
5 p = 5 x 4
5 p = 20
5 u + 10 = 5 p
5 u + 10 = 20
5 u = 20 - 10
5 u = 10
1 u = 10 ÷ 5 = 2
Total number of children at first
= 7 u
= 7 x 2
= 14
Answer(s): 14