| U | = | 12 | + | ( | ( | U | − | 12 | ) | ÷ | 10 | ) | × | 10 |
| Right side of the equation = | 12 | + | ( | U | − | 12 | ) | ÷ | 10 | × | 10 |
| = | 12 | + | ( | U | − | 12 | ) | × | 1 |
| = | 12 | + | U | × | 1 | − | 12 | × | 1 |
| = | 12 | + | U | × | 1 | − | 12 |
| = | 0 | + | 1 | U |
| U | = | 1 | U |
| U | − | 1 | U | = | 0 |
| 0 | U | = | 0 |
| U | = | 8 | + | ( | ( | U | − | 8 | ) | ÷ | 20 | ) | × | 20 |
| Right side of the equation = | 8 | + | ( | U | − | 8 | ) | ÷ | 20 | × | 20 |
| = | 8 | + | ( | U | − | 8 | ) | × | 1 |
| = | 8 | + | U | × | 1 | − | 8 | × | 1 |
| = | 8 | + | U | × | 1 | − | 8 |
| = | 0 | + | 1 | U |
| U | = | 1 | U |
| U | − | 1 | U | = | 0 |
| 0 | U | = | 0 |