| ( | x | − | 5 | ) | × | 25 | + | 500 | = | 25 | x | × | 9 10 | + | 500 | × | 9 10 |
| 方程左边 = | x | × | 25 | − | 5 | × | 25 | + | 500 |
| = | x | × | 25 | − | 125 | + | 500 |
| = | 25 | x | + | 375 |
| 25 | x | + | 375 | = | 25 | x | × | 9 10 | + | 500 | × | 9 10 |
| 方程右边 = | 45 2 | x | + | 450 |
| 25 | x | + | 375 | = | 45 2 | x | + | 450 |
| 25 | x | − | 45 2 | x | = | 450 | − | 375 |
5 2 | x | = | 450 | − | 375 |
5 2 | x | = | 75 |
| x | = | 75 | ÷ | 5 2 |
| = | 75 | × | 2 5 |
| = | 15 | × | 2 |
| x | = | 30 |