| ( | 9200 | + | 20 | + | x | ) | × | 31 1000 | = | 4 | x |
| 方程左边 = | 9200 | × | 31 1000 | + | 20 | × | 31 1000 | + | x | × | 31 1000 |
| = | 1426 5 | + | 31 50 | + | x | × | 31 1000 |
| = | 14291 50 | + | 31 1000 | x |
14291 50 | + | 31 1000 | x | = | 4 | x |
31 1000 | x | − | 4 | x | = | - | 14291 50 |
| - | 3969 1000 | x | = | - | 14291 50 |
14291 50 | = | 3969 1000 | x |
3969 1000 | x | = | 14291 50 |
| x | = | 14291 50 | ÷ | 3969 1000 |
| = | 14291 50 | × | 1000 3969 |
| = | 14291 | × | 20 3969 |
| x | = | 285820 3969 |
| x | = | 72.013102 |