| 500 | × | 9 10 | X | + | ( | X | − | 500 | ) | × | 4 5 | = | 490 |
| 方程左边 = | 450 | X | + | ( | X | − | 500 | ) | × | 4 5 |
| 450 | X | + | ( | X | − | 500 | ) | × | 4 5 | = | 490 |
| 方程左边 = | 450 | X | + | X | × | 4 5 | − | 500 | × | 4 5 |
| = | 450 | X | + | X | × | 4 5 | − | 400 |
| = | 2254 5 | X | − | 400 |
2254 5 | X | − | 400 | = | 490 |
2254 5 | X | = | 490 | + | 400 |
2254 5 | X | = | 890 |
| X | = | 890 | ÷ | 2254 5 |
| = | 890 | × | 5 2254 |
| = | 445 | × | 5 1127 |
| X | = | 2225 1127 |
| X | = | 1.974268 |