| ( | x | + | 50 100 | ) | × | 90 100 | − | 50 | − | x | = | 370 |
| 方程左边 = | x | × | 90 100 | + | 50 100 | × | 90 100 | − | 50 | − | x |
| = | x | × | 90 100 | + | 9 20 | − | 50 | − | x |
| = | - | 1 10 | x | − | 991 20 |
| - | 1 10 | x | − | 991 20 | = | 370 |
| - | 1 10 | x | = | 370 | + | 991 20 |
| - | 1 10 | x | = | 8391 20 |
| - | 8391 20 | = | 1 10 | x |
1 10 | x | = | - | 8391 20 |
| x | = | - | 8391 20 | ÷ | 1 10 |
| = | - | 8391 20 | × | 10 |
| = | - | 8391 2 | × | 1 |
| x | = | - | 8391 2 |
| x | = | - 4195.5 |