| x | = | 80 | − | 5 | ( | 2 | x | + | 5 | ) | + | ( | 5 | × | 2 | ) |
| 方程右边 = | 80 | − | 5 | × | 2 | x | − | 5 | × | 5 | + | ( | 5 | × | 2 | ) |
| = | 80 | − | 10 | x | − | 25 | + | ( | 5 | × | 2 | ) |
| = | 55 | − | 10 | x | + | ( | 5 | × | 2 | ) |
| = | 55 | − | 10 | x | + | 5 | × | 2 |
| = | 55 | − | 10 | x | + | 10 |
| = | 65 | − | 10 | x |
| x | = | 65 | − | 10 | x |
| x | + | 10 | x | = | 65 |
| 11 | x | = | 65 |
| x | = | 65 | ÷ | 11 |
| = | 65 | × | 1 11 |
| x | = | 65 11 |
| x | = | 5.909091 |