| ( | 3 | ÷ | 2 | + | 20 | ) | ( | - | 3 | ) | ( | 90 | − | x | ) | = | 65 |
| 方程左边 = | 3 | ÷ | 2 | × | ( | - | 3 | ) | ( | 90 | − | x | ) | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | 3 2 | ( | - | 3 | ) | ( | 90 | − | x | ) | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | - | 3 2 | × | 3 | ( | 90 | − | x | ) | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | - | 9 2 | ( | 90 | − | x | ) | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | - | 9 2 | × | 90 | + | 9 2 | x | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | - | 405 | + | 9 2 | x | + | 20 | ( | - | 3 | ) | ( | 90 | − | x | ) |
| = | - | 405 | + | 9 2 | x | − | 20 | × | 3 | ( | 90 | − | x | ) |
| = | - | 405 | + | 9 2 | x | − | 60 | ( | 90 | − | x | ) |
| = | - | 405 | + | 9 2 | x | − | 60 | × | 90 | + | 60 | x |
| = | - | 405 | + | 9 2 | x | − | 5400 | + | 60 | x |
| = | - | 5805 | + | 129 2 | x |
| - | 5805 | + | 129 2 | x | = | 65 |
129 2 | x | = | 65 | + | 5805 |
129 2 | x | = | 5870 |
| x | = | 5870 | ÷ | 129 2 |
| = | 5870 | × | 2 129 |
| x | = | 11740 129 |
| x | = | 91.007752 |