| A | × | 5 100 | ( | 1750 | − | 70 | ) | ÷ | 2500 | − | A | × | 21 20 | × | 4 100 | × | 80 100 | = | 0 |
| 方程左边 = | A | × | 1 50000 | ( | 1750 | − | 70 | ) | − | A | × | 21 625 |
| A | × | 1 50000 | ( | 1750 | − | 70 | ) | − | 21 625 | A | = | 0 |
| 方程左边 = | A | × | 1 50000 | × | 1750 | − | A | × | 1 50000 | × | 70 | − | 21 625 | A |
| = | A | × | 7 200 | − | A | × | 7 5000 | − | 21 625 | A |
| = | 0 | A |
| 0 | = | 0 |
| = | 0 | − | 0 |