Peter had
310 as many erasers as Eva. After Peter gave away 21 erasers, he had 70 less erasers than Eva. How many erasers did Eva have?
| |
Peter |
Eva |
| Before |
3 u |
10 u |
| Change |
- 21 |
|
| After |
3 u - 21 |
10 u |
Eva had 70 more erasers than Peter in the end. So, if Peter had another 70 erasers, he would have the same number of erasers as Eva.
10 u = 3 u - 21 + 70
10 u - 3 u = 70 - 21
7 u = 49
1 u = 49 ÷ 7 = 7
Number of erasers that Eva had at first
= 10 u
= 10 x 7
= 70
Answer: 70
