Some children board a school bus.
At Bus Stop A,
35 of them alight
and 9 children board.
At Bus Stop B,
79 of the children alight
and 7 board.
If there are 13 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 |
- 3 u + 9 |
|
After 1 |
2 u + 9 |
9 p |
Change 2 At Bus Stop B |
|
- 7 p + 7 |
After 2 |
|
13 |
Working backwards.
Number of children in the end = 13
9 p - 7 p = 13 - 7
2 p = 6
1 p = 6 ÷ 2 = 3
9 p = 9 x 3
9 p = 27
2 u + 9 = 9 p
2 u + 9 = 27
2 u = 27 - 9
2 u = 18
1 u = 18 ÷ 2 = 9
Total number of children at first
= 5 u
= 5 x 9
= 45
Answer(s): 45