| 2 | ( | X | × | 3 | + | 1 | ) | + | 5 | = | 2 | ( | X | × | 5 2 | + | 1 | ) | − | 115 |
| 方程左边 = | 2 | X | × | 3 | + | 2 | × | 1 | + | 5 |
| = | 6 | X | + | 2 | + | 5 |
| = | 6 | X | + | 7 |
| 6 | X | + | 7 | = | 2 | ( | X | × | 5 2 | + | 1 | ) | − | 115 |
| 方程右边 = | 2 | X | × | 5 2 | + | 2 | × | 1 | − | 115 |
| = | 5 | X | + | 2 | − | 115 |
| = | 5 | X | − | 113 |
| 6 | X | + | 7 | = | 5 | X | − | 113 |
| 6 | X | − | 5 | X | = | - | 113 | − | 7 |
| X | = | - | 113 | − | 7 |
| X | = | - | 113 | − | 7 |
| X | = | - | 120 |