| ( | 5 | − | U | ) | ÷ | 10 | + | ( | 12 | − | U | ) | ÷ | 20 | = | U | ÷ | 10 |
| 方程左边 = | 5 | × | 1 10 | − | U | × | 1 10 | + | ( | 12 | − | U | ) | × | 1 20 |
| = | 1 2 | − | U | × | 1 10 | + | ( | 12 | − | U | ) | × | 1 20 |
| = | 1 2 | − | 1 10 | U | + | 12 | × | 1 20 | − | U | × | 1 20 |
| = | 1 2 | − | 1 10 | U | + | 3 5 | − | U | × | 1 20 |
| = | 11 10 | − | 3 20 | U |
11 10 | − | 3 20 | U | = | U | ÷ | 10 |
| - | 3 20 | U | − | 1 10 | U | = | - | 11 10 |
| - | 1 4 | U | = | - | 11 10 |
11 10 | = | 1 4 | U |
1 4 | U | = | 11 10 |
| U | = | 11 10 | ÷ | 1 4 |
| = | 11 10 | × | 4 |
| = | 11 5 | × | 2 |
| U | = | 22 5 |
| U | = | 4.4 |