| 1300 | ( | 12000 | − | x | ) | = | 1500 | ( | 10000 | − | x | ) |
| 方程左边 = | 1300 | × | 12000 | − | 1300 | x |
| = | 15600000 | − | 1300 | x |
| 15600000 | − | 1300 | x | = | 1500 | ( | 10000 | − | x | ) |
| 方程右边 = | 1500 | × | 10000 | − | 1500 | x |
| = | 15000000 | − | 1500 | x |
| 15600000 | − | 1300 | x | = | 15000000 | − | 1500 | x |
| - | 1300 | x | + | 1500 | x | = | 15000000 | − | 15600000 |
| 200 | x | = | 15000000 | − | 15600000 |
| 200 | x | = | - | 600000 |
| x | = | - | 600000 | ÷ | 200 |
| = | - | 600000 | × | 1 200 |
| = | - | 3000 | × | 1 |
| x | = | - | 3000 |