Sarah had the same number of black, pink and grey erasers at first. After giving some black and pink erasers and 80 grey erasers away, Sarah had 156 erasers left. There were 2 times as many black erasers as pink erasers left. The number of grey erasers left was 49 fewer than the number of black erasers left. How many grey erasers did she have at first?
| |
Pink |
Black |
Grey |
Total |
| Before |
2 u + 31 |
2 u + 31 |
2 u + 31 |
|
| Change |
- 1 u - 31 |
- 31 |
- 80 |
|
| After |
1 u |
2 u |
2 u - 49 |
156 |
Sarah had the same number of black, pink and grey erasers at first.
Total number of erasers in the end
= 1 u + 2 u + 2 u - 49
= 5 u - 49
5 u - 49 = 156
5 u = 156 + 49
5 u = 205
1 u = 205 ÷ 5 = 41
Number of grey erasers that Sarah had at first
= 2 u - 49 + 80
= 2 u + 31
= 2 x 41 + 31
= 113
Answer(s): 113
