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