| x | = | 80 | − | 5 | ( | 2 | x | + | 5 | ) | − | 2 | ( | 5 | × | 2 | ) |
| 方程右边 = | 80 | − | 5 | × | 2 | x | − | 5 | × | 5 | − | 2 | ( | 5 | × | 2 | ) |
| = | 80 | − | 10 | x | − | 25 | − | 2 | ( | 5 | × | 2 | ) |
| = | 55 | − | 10 | x | − | 2 | ( | 5 | × | 2 | ) |
| = | 55 | − | 10 | x | − | 2 | × | 5 | × | 2 |
| = | 55 | − | 10 | x | − | 20 |
| = | 35 | − | 10 | x |
| x | = | 35 | − | 10 | x |
| x | + | 10 | x | = | 35 |
| 11 | x | = | 35 |
| x | = | 35 | ÷ | 11 |
| = | 35 | × | 1 11 |
| x | = | 35 11 |
| x | = | 3.181818 |