Last week, Luke had a total of 198 black and red files. Two weeks later, he sold
34 of all the black files and bought another 17 red files. Now he has the same number of black and red files. How many files does he have in the end?
| |
Black |
Red |
Total |
| Before |
4 u |
1 u - 17 |
5 u - 17 |
| Change |
- 3 u |
+ 17 |
|
| After |
1 u |
1 u |
|
Comparing the black
and red files in the end |
1 |
1 |
|
Total number of files at first
= 4 u + 1 u - 17
= 5 u - 17
5 u - 17 = 198
5 u = 198 + 17
5 u = 215
1 u = 215 ÷ 5 = 43
Number of files that he has in the end
= 1 u + 1 u
= 2 u
= 2 x 43
= 86
Answer(s): 86
