| 12000 | ( | X | − | 200 | ) | − | 720000 | − | 12000 | X | × | 5 100 | = | ( | 720000 | + | 12000 | × | 200 | ) | × | 20 100 |
| 方程左边 = | 12000 | ( | X | − | 200 | ) | − | 720000 | − | 600 | X |
| 12000 | ( | X | − | 200 | ) | − | 720000 | − | 600 | X | = | ( | 720000 | + | 12000 | × | 200 | ) | × | 20 100 |
| 方程左边 = | 12000 | X | − | 12000 | × | 200 | − | 720000 | − | 600 | X |
| = | 12000 | X | − | 2400000 | − | 720000 | − | 600 | X |
| = | 11400 | X | − | 3120000 |
| 11400 | X | − | 3120000 | = | ( | 720000 | + | 12000 | × | 200 | ) | × | 20 100 |
| 方程右边 = | 720000 | × | 20 100 | + | 12000 | × | 200 | × | 20 100 |
| = | 144000 | + | 480000 |
| = | 624000 |
| 11400 | X | − | 3120000 | = | 624000 |
| 11400 | X | = | 624000 | + | 3120000 |
| 11400 | X | = | 3744000 |
| X | = | 3744000 | ÷ | 11400 |
| = | 3744000 | × | 1 11400 |
| = | 6240 | × | 1 19 |
| X | = | 6240 19 |
| X | = | 328.421053 |