| 10 | ( | 4 5 | x | − | ( | x | − | 60 | ) | ) | = | 15 | ( | ( | x | − | 30 | ) | − | ( | x | − | 60 | ) | ) |
| 方程左边 = | 10 | × | 4 5 | x | − | 10 | ( | x | − | 60 | ) |
| = | 8 | x | − | 10 | ( | x | − | 60 | ) |
| = | 8 | x | − | 10 | x | + | 10 | × | 60 |
| = | 8 | x | − | 10 | x | + | 600 |
| = | - | 2 | x | + | 600 |
| - | 2 | x | + | 600 | = | 15 | ( | ( | x | − | 30 | ) | − | ( | x | − | 60 | ) | ) |
| 方程右边 = | 15 | ( | x | − | 30 | ) | − | 15 | ( | x | − | 60 | ) |
| = | 15 | x | − | 15 | × | 30 | − | 15 | ( | x | − | 60 | ) |
| = | 15 | x | − | 450 | − | 15 | ( | x | − | 60 | ) |
| = | 15 | x | − | 450 | − | 15 | x | + | 15 | × | 60 |
| = | 15 | x | − | 450 | − | 15 | x | + | 900 |
| = | 0 | x | + | 450 |
| - | 2 | x | + | 600 | = | 0 | x | + | 450 |
| - | 2 | x | = | 450 | − | 600 |
| - | 2 | x | = | - | 150 |
| 150 | = | 2 | x |
| 2 | x | = | 150 |
| x | = | 150 | ÷ | 2 |
| = | 150 | × | 1 2 |
| = | 75 | × | 1 |
| x | = | 75 |