Some children board a school bus.
At Bus Stop A,
13 of them alight
and 8 children board.
At Bus Stop B,
47 of the children alight
and 8 board.
If there are 20 children on the bus now,
how many children are on the bus at first?
|
Number of children |
Before |
3 u |
|
Change 1 At Bus Stop A |
- 1 u + 8 |
|
After 1 |
2 u + 8 |
7 p |
Change 2 At Bus Stop B |
|
- 4 p + 8 |
After 2 |
|
20 |
Working backwards.
Number of children in the end = 20
7 p - 4 p = 20 - 8
3 p = 12
1 p = 12 ÷ 3 = 4
7 p = 7 x 4
7 p = 28
2 u + 8 = 7 p
2 u + 8 = 28
2 u = 28 - 8
2 u = 20
1 u = 20 ÷ 2 = 10
Total number of children at first
= 3 u
= 3 x 10
= 30
Answer(s): 30