| ( | 2392 25 | − | X | ) | ( | 1309 20 | − | X | ) | = | 4050 |
| 方程左边 = | 2392 25 | ( | 1309 20 | − | X | ) | − | X | ( | 1309 20 | − | X | ) |
| = | 2392 25 | × | 1309 20 | − | 2392 25 | X | − | X | ( | 1309 20 | − | X | ) |
| = | 782782 125 | − | 2392 25 | X | − | X | ( | 1309 20 | − | X | ) |
| = | 782782 125 | − | 2392 25 | X | − | X | × | 1309 20 | + | X | X |
| = | 782782 125 | − | 16113 100 | X | + | X | X |
782782 125 | − | 16113 100 | X | + | X | X | = | 4050 |