| x | − | 7 20 | x | − | 23000 | − | ( | x | − | 7 20 | x | − | 23000 | ) | ÷ | 2 | = | 12000 |
| 方程左边 = | 13 20 | x | − | 23000 | − | ( | x | − | 7 20 | x | − | 23000 | ) | × | 1 2 |
13 20 | x | − | 23000 | − | ( | x | − | 7 20 | x | − | 23000 | ) | × | 1 2 | = | 12000 |
| 方程左边 = | 13 20 | x | − | 23000 | − | x | × | 1 2 | + | 7 20 | x | × | 1 2 | + | 23000 | × | 1 2 |
| = | 13 20 | x | − | 23000 | − | x | × | 1 2 | + | 7 40 | x | + | 11500 |
| = | 13 40 | x | − | 11500 |
13 40 | x | − | 11500 | = | 12000 |
13 40 | x | = | 12000 | + | 11500 |
13 40 | x | = | 23500 |
| x | = | 23500 | ÷ | 13 40 |
| = | 23500 | × | 40 13 |
| x | = | 940000 13 |
| x | = | 72307.692308 |