Some children board a school bus.
At Bus Stop A,
710 of them alight
and 3 children board.
At Bus Stop B,
13 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 |
10 u |
|
Change 1 At Bus Stop A |
- 7 u + 3 |
|
After 1 |
3 u + 3 |
3 p |
Change 2 At Bus Stop B |
|
- 1 p + 7 |
After 2 |
|
15 |
Working backwards.
Number of children in the end = 15
3 p - 1 p = 15 - 7
2 p = 8
1 p = 8 ÷ 2 = 4
3 p = 3 x 4
3 p = 12
3 u + 3 = 3 p
3 u + 3 = 12
3 u = 12 - 3
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of children at first
= 10 u
= 10 x 3
= 30
Answer(s): 30