| 42 | − | 5 | x | = | 3 | x | − | 18 |
| - | 5 | x | − | 3 | x | = | - | 18 | − | 42 |
| - | 8 | x | = | - | 18 | − | 42 |
| - | 8 | x | = | - | 60 |
| 60 | = | 8 | x |
| 8 | x | = | 60 |
| x | = | 60 | ÷ | 8 |
| = | 60 | × | 1 8 |
| = | 15 | × | 1 2 |
| x | = | 15 2 |
| x | = | 7.5 |
8 5 | + | ( | x | − | 4 5 | ) | ÷ | 1 5 | = | 16 5 |
| 方程左边 = | 8 5 | + | x | × | 5 | − | 4 5 | × | 5 |
| = | 8 5 | + | x | × | 5 | − | 4 |
| = | - | 12 5 | + | 5 | x |
| - | 12 5 | + | 5 | x | = | 16 5 |
| 5 | x | = | 16 5 | + | 12 5 |
| 5 | x | = | 28 5 |
| x | = | 28 5 | ÷ | 5 |
| = | 28 5 | × | 1 5 |
| x | = | 28 25 |
| x | = | 1.12 |