| 65 | + | ( | 3 2 | x | + | 20 | ) | ( | - | 3 10 | ) | ( | 90 | − | x | ) | = | 3 2 | x | + | 20 |
| Left side of the equation = | 65 | + | 3 2 | x | ( | - | 3 10 | ) | ( | 90 | − | x | ) | + | 20 | ( | - | 3 10 | ) | ( | 90 | − | x | ) |
| = | 65 | − | 3 2 | x | × | 3 10 | ( | 90 | − | x | ) | + | 20 | ( | - | 3 10 | ) | ( | 90 | − | x | ) |
| = | 65 | − | 9 20 | x | ( | 90 | − | x | ) | + | 20 | ( | - | 3 10 | ) | ( | 90 | − | x | ) |
| = | 65 | − | 9 20 | x | × | 90 | + | 9 20 | x | x | + | 20 | ( | - | 3 10 | ) | ( | 90 | − | x | ) |
| = | 65 | − | 81 2 | x | + | 9 20 | x | x | + | 20 | ( | - | 3 10 | ) | ( | 90 | − | x | ) |
| = | 65 | − | 81 2 | x | + | 9 20 | x | x | − | 20 | × | 3 10 | ( | 90 | − | x | ) |
| = | 65 | − | 81 2 | x | + | 9 20 | x | x | − | 6 | ( | 90 | − | x | ) |
| = | 65 | − | 81 2 | x | + | 9 20 | x | x | − | 6 | × | 90 | + | 6 | x |
| = | 65 | − | 81 2 | x | + | 9 20 | x | x | − | 540 | + | 6 | x |
| = | - | 475 | − | 69 2 | x | + | 9 20 | x | x |
| - | 475 | − | 69 2 | x | + | 9 20 | x | x | = | 3 2 | x | + | 20 |