| 6 | x | + | 10 | ( | 100 | − | x | ) | = | 1300 | − | 378 |
| 方程左边 = | 6 | x | + | 10 | × | 100 | − | 10 | x |
| = | 6 | x | + | 1000 | − | 10 | x |
| = | - | 4 | x | + | 1000 |
| - | 4 | x | + | 1000 | = | 1300 | − | 378 |
| 方程右边 = | 922 |
| - | 4 | x | + | 1000 | = | 922 |
| - | 4 | x | = | 922 | − | 1000 |
| - | 4 | x | = | - | 78 |
| 78 | = | 4 | x |
| 4 | x | = | 78 |
| x | = | 78 | ÷ | 4 |
| = | 78 | × | 1 4 |
| = | 39 | × | 1 2 |
| x | = | 39 2 |
| x | = | 19.5 |