27 10 | ( | 20 | − | x | ) | + | 69 10 | ( | 30 | + | x | ) | − | 113 | = | 929 5 |
| 方程左边 = | 27 10 | × | 20 | − | 27 10 | x | + | 69 10 | ( | 30 | + | x | ) | − | 113 |
| = | 54 | − | 27 10 | x | + | 69 10 | ( | 30 | + | x | ) | − | 113 |
| = | - | 59 | − | 27 10 | x | + | 69 10 | ( | 30 | + | x | ) |
| = | - | 59 | − | 27 10 | x | + | 69 10 | × | 30 | + | 69 10 | x |
| = | - | 59 | − | 27 10 | x | + | 207 | + | 69 10 | x |
| = | 148 | + | 21 5 | x |
| 148 | + | 21 5 | x | = | 929 5 |
21 5 | x | = | 929 5 | − | 148 |
21 5 | x | = | 189 5 |
| x | = | 189 5 | ÷ | 21 5 |
| = | 189 5 | × | 5 21 |
| = | 9 | × | 1 |
| x | = | 9 |