| 85 | x | + | 90 | ( | 25 | − | x | ) | = | 25 | × | 2202 25 |
| 方程左边 = | 85 | x | + | 90 | × | 25 | − | 90 | x |
| = | 85 | x | + | 2250 | − | 90 | x |
| = | - | 5 | x | + | 2250 |
| - | 5 | x | + | 2250 | = | 25 | × | 2202 25 |
| 方程右边 = | 2202 |
| - | 5 | x | + | 2250 | = | 2202 |
| - | 5 | x | = | 2202 | − | 2250 |
| - | 5 | x | = | - | 48 |
| 48 | = | 5 | x |
| 5 | x | = | 48 |
| x | = | 48 | ÷ | 5 |
| = | 48 | × | 1 5 |
| x | = | 48 5 |
| x | = | 9.6 |