Charlie had 5 times as many blue files as grey files. After giving away 7 blue files and buying another 25 grey files, he had an equal number of blue and grey files. How many blue files did Charlie have at first?
| |
Blue files |
Grey files |
| Before |
5 u |
1 u |
| Change |
- 7 |
+ 25 |
| After |
5 u - 7 |
1 u + 25 |
The number of blue and grey files is the same in the end.
5 u - 7 = 1 u + 25
5 u - 1 u = 25 + 7
4 u = 7 + 25
4 u = 32
1 u = 32 ÷ 4 = 8
Number of blue files that Charlie had at first
= 5 u
= 5 x 8
= 40
Answer(s): 40
