| 100 | x | + | 12 | x | − | ( | 15 | x | + | 123 | ) | = | x | + | 12 |
| 方程左边 = | 112 | x | − | ( | 15 | x | + | 123 | ) |
| 112 | x | − | ( | 15 | x | + | 123 | ) | = | x | + | 12 |
| 方程左边 = | 112 | x | − | 15 | x | − | 123 |
| = | 97 | x | − | 123 |
| 97 | x | − | 123 | = | x | + | 12 |
| 97 | x | − | x | = | 12 | + | 123 |
| 96 | x | = | 12 | + | 123 |
| 96 | x | = | 135 |
| x | = | 135 | ÷ | 96 |
| = | 135 | × | 1 96 |
| = | 45 | × | 1 32 |
| x | = | 45 32 |
| x | = | 1.40625 |