4 5 | x | − | 30 | + | 10 | = | 3 4 | ( | x | − | 10 | ) |
| 方程左边 = | 4 5 | x | − | 20 |
4 5 | x | − | 20 | = | 3 4 | ( | x | − | 10 | ) |
| 方程右边 = | 3 4 | x | − | 3 4 | × | 10 |
| = | 3 4 | x | − | 15 2 |
4 5 | x | − | 20 | = | 3 4 | x | − | 15 2 |
4 5 | x | − | 3 4 | x | = | - | 15 2 | + | 20 |
1 20 | x | = | - | 15 2 | + | 20 |
1 20 | x | = | 25 2 |
| x | = | 25 2 | ÷ | 1 20 |
| = | 25 2 | × | 20 |
| = | 25 | × | 10 |
| x | = | 250 |