| ( | X | − | 40 | − | 20 | ) | ( | 1 | − | 20 100 | ) | ÷ | 800 | = | ( | X | − | 40 | − | 45 | ) | ( | 1 | − | 20 100 | ) | ÷ | 800 |
| 方程左边 = | X | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 40 | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 20 | ( | 1 | − | 20 100 | ) | × | 1 800 |
| = | X | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | X | × | 1 | × | 1 800 | − | X | × | 20 100 | × | 1 800 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | X | × | 1 800 | − | X | × | 1 4000 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | × | 1 | + | 1 20 | × | 20 100 | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | + | 1 100 | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 25 | − | 1 40 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 25 | − | 1 40 | × | 1 | + | 1 40 | × | 20 100 |
| = | 1 1000 | X | − | 1 25 | − | 1 40 | + | 1 200 |
| = | 1 1000 | X | − | 3 50 |
1 1000 | X | − | 3 50 | = | ( | X | − | 40 | − | 45 | ) | ( | 1 | − | 20 100 | ) | ÷ | 800 |
| 方程右边 = | X | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 40 | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 45 | ( | 1 | − | 20 100 | ) | × | 1 800 |
| = | X | ( | 1 | − | 20 100 | ) | × | 1 800 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | X | × | 1 | × | 1 800 | − | X | × | 20 100 | × | 1 800 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | X | × | 1 800 | − | X | × | 1 4000 | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | ( | 1 | − | 20 100 | ) | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | × | 1 | + | 1 20 | × | 20 100 | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 20 | + | 1 100 | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 25 | − | 9 160 | ( | 1 | − | 20 100 | ) |
| = | 1 1000 | X | − | 1 25 | − | 9 160 | × | 1 | + | 9 160 | × | 20 100 |
| = | 1 1000 | X | − | 1 25 | − | 9 160 | + | 9 800 |
| = | 1 1000 | X | − | 17 200 |
1 1000 | X | − | 3 50 | = | 1 1000 | X | − | 17 200 |
1 1000 | X | − | 1 1000 | X | = | - | 17 200 | + | 3 50 |
| 0 | X | = | - | 17 200 | + | 3 50 |
| 0 | X | = | - | 1 40 |