| 45 | ( | 70 | + | x | ) | × | 3825 | = | 0 |
| 方程左边 = | 172125 | ( | 70 | + | x | ) |
| 172125 | ( | 70 | + | x | ) | = | 0 |
| 方程左边 = | 172125 | × | 70 | + | 172125 | x |
| = | 12048750 | + | 172125 | x |
| 12048750 | + | 172125 | x | = | 0 |
| 172125 | x | = | 0 | − | 12048750 |
| 172125 | x | = | - | 12048750 |
| x | = | - | 12048750 | ÷ | 172125 |
| = | - | 12048750 | × | 1 172125 |
| = | - | 70 | × | 1 |
| x | = | - | 70 |