| 72 | = | x | − | 10 | + | ( | x | − | 10 | ) | ÷ | 30 |
| 方程右边 = | x | − | 10 | + | x | × | 1 30 | − | 10 | × | 1 30 |
| = | x | − | 10 | + | x | × | 1 30 | − | 1 3 |
| = | 31 30 | x | − | 31 3 |
| 72 | = | 31 30 | x | − | 31 3 |
| - | 31 30 | x | = | - | 31 3 | − | 72 |
| - | 31 30 | x | = | - | 247 3 |
247 3 | = | 31 30 | x |
31 30 | x | = | 247 3 |
| x | = | 247 3 | ÷ | 31 30 |
| = | 247 3 | × | 30 31 |
| = | 247 | × | 10 31 |
| x | = | 2470 31 |
| x | = | 79.677419 |