| 6 | − | 3 | ( | 3 | − | 90 | ÷ | ( | 2 | x | − | 2 | ) | ) | = | 12 |
| 6 | − | 3 | × | 3 | + | 3 | × | 90 | ÷ | ( | 2 | x | − | 2 | ) | = | 12 |
| 6 | − | 9 | + | 270 | ÷ | ( | 2 | x | − | 2 | ) | = | 12 |
| - | 3 | + | 270 | ÷ | ( | 2 | x | − | 2 | ) | = | 12 |
| 方程两边同时乘以: | ( | 2 | x | − | 2 | ) |
| - | 3 | ( | 2 | x | − | 2 | ) | + | 270 | = | 12 | ( | 2 | x | − | 2 | ) |
| - | 3 | × | 2 | x | + | 3 | × | 2 | + | 270 | = | 12 | ( | 2 | x | − | 2 | ) |
| - | 3 | × | 2 | x | + | 3 | × | 2 | + | 270 | = | 12 | × | 2 | x | − | 12 | × | 2 |
| - | 6 | x | + | 6 | + | 270 | = | 24 | x | − | 24 |
| - | 6 | x | + | 276 | = | 24 | x | − | 24 |
| - | 6 | x | − | 24 | x | = | - | 24 | − | 276 |
| - | 30 | x | = | - | 24 | − | 276 |
| - | 30 | x | = | - | 300 |
| 300 | = | 30 | x |
| 30 | x | = | 300 |
| x | = | 300 | ÷ | 30 |
| = | 300 | × | 1 30 |
| = | 10 | × | 1 |
| x | = | 10 |