| ( | 4 | X | − | 2 | ) | + | ( | 5 | X | + | 10 | ) | + | ( | 3 | X | − | 8 | ) | + | 27 | = | 180 |
| 方程左边 = | 4 | X | − | 2 | + | ( | 5 | X | + | 10 | ) | + | ( | 3 | X | − | 8 | ) | + | 27 |
| = | 4 | X | + | 25 | + | ( | 5 | X | + | 10 | ) | + | ( | 3 | X | − | 8 | ) |
| = | 4 | X | + | 25 | + | 5 | X | + | 10 | + | ( | 3 | X | − | 8 | ) |
| = | 9 | X | + | 35 | + | ( | 3 | X | − | 8 | ) |
| = | 9 | X | + | 35 | + | 3 | X | − | 8 |
| = | 12 | X | + | 27 |
| 12 | X | + | 27 | = | 180 |
| 12 | X | = | 180 | − | 27 |
| 12 | X | = | 153 |
| X | = | 153 | ÷ | 12 |
| = | 153 | × | 1 12 |
| = | 51 | × | 1 4 |
| X | = | 51 4 |
| X | = | 12.75 |