Eric had 3 times as many brown files as green files. After giving away 5 brown files and buying another 15 green files, he had an equal number of brown and green files. How many brown files did Eric have at first?
| |
Brown files |
Green files |
| Before |
3 u |
1 u |
| Change |
- 5 |
+ 15 |
| After |
3 u - 5 |
1 u + 15 |
The number of brown and green files is the same in the end.
3 u - 5 = 1 u + 15
3 u - 1 u = 15 + 5
2 u = 5 + 15
2 u = 20
1 u = 20 ÷ 2 = 10
Number of brown files that Eric had at first
= 3 u
= 3 x 10
= 30
Answer(s): 30
