| 7 | ( | x | + | 12 | ) | = | 5 | ( | 4 | x | − | 12 | ) |
| 方程左边 = | 7 | x | + | 7 | × | 12 |
| = | 7 | x | + | 84 |
| 7 | x | + | 84 | = | 5 | ( | 4 | x | − | 12 | ) |
| 方程右边 = | 5 | × | 4 | x | − | 5 | × | 12 |
| = | 20 | x | − | 60 |
| 7 | x | + | 84 | = | 20 | x | − | 60 |
| 7 | x | − | 20 | x | = | - | 60 | − | 84 |
| - | 13 | x | = | - | 60 | − | 84 |
| - | 13 | x | = | - | 144 |
| 144 | = | 13 | x |
| 13 | x | = | 144 |
| x | = | 144 | ÷ | 13 |
| = | 144 | × | 1 13 |
| x | = | 144 13 |
| x | = | 11.076923 |