13 20 | ( | 1 | − | x | ) | = | 369 1000 |
| 方程左边 = | 13 20 | × | 1 | − | 13 20 | x |
| = | 13 20 | − | 13 20 | x |
13 20 | − | 13 20 | x | = | 369 1000 |
| - | 13 20 | x | = | 369 1000 | − | 13 20 |
| - | 13 20 | x | = | - | 281 1000 |
281 1000 | = | 13 20 | x |
13 20 | x | = | 281 1000 |
| x | = | 281 1000 | ÷ | 13 20 |
| = | 281 1000 | × | 20 13 |
| = | 281 50 | × | 1 13 |
| x | = | 281 650 |
| x | = | 0.432308 |