Some children board a school bus.
At Bus Stop A,
310 of them alight
and 3 children board.
At Bus Stop B,
14 of the children alight
and 2 board.
If there are 20 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 |
- 3 u + 3 |
|
After 1 |
7 u + 3 |
4 p |
Change 2 At Bus Stop B |
|
- 1 p + 2 |
After 2 |
|
20 |
Working backwards.
Number of children in the end = 20
4 p - 1 p = 20 - 2
3 p = 18
1 p = 18 ÷ 3 = 6
4 p = 4 x 6
4 p = 24
7 u + 3 = 4 p
7 u + 3 = 24
7 u = 24 - 3
7 u = 21
1 u = 21 ÷ 7 = 3
Total number of children at first
= 10 u
= 10 x 3
= 30
Answer(s): 30