| ( | 5 | − | U | ) | ÷ | 10 | + | ( | 12 | − | U | ) | ÷ | 10 | = | U | ÷ | 10 |
| 方程左边 = | 5 | × | 1 10 | − | U | × | 1 10 | + | ( | 12 | − | U | ) | × | 1 10 |
| = | 1 2 | − | U | × | 1 10 | + | ( | 12 | − | U | ) | × | 1 10 |
| = | 1 2 | − | 1 10 | U | + | 12 | × | 1 10 | − | U | × | 1 10 |
| = | 1 2 | − | 1 10 | U | + | 6 5 | − | U | × | 1 10 |
| = | 17 10 | − | 1 5 | U |
17 10 | − | 1 5 | U | = | U | ÷ | 10 |
| - | 1 5 | U | − | 1 10 | U | = | - | 17 10 |
| - | 3 10 | U | = | - | 17 10 |
17 10 | = | 3 10 | U |
3 10 | U | = | 17 10 |
| U | = | 17 10 | ÷ | 3 10 |
| = | 17 10 | × | 10 3 |
| = | 17 | × | 1 3 |
| U | = | 17 3 |
| U | = | 5.666667 |