| 3 | ( | - | ( | 4 | ( | x | − | 14 | ) | + | 5 | ) | + | 15 | ) | + | 3 | = | - | 3 | x | + | 120 |
| Left side of the equation = | - | 3 | ( | 4 | ( | x | − | 14 | ) | + | 5 | ) | + | 3 | × | 15 | + | 3 |
| = | - | 3 | ( | 4 | ( | x | − | 14 | ) | + | 5 | ) | + | 45 | + | 3 |
| = | - | 3 | ( | 4 | ( | x | − | 14 | ) | + | 5 | ) | + | 48 |
| = | - | 3 | × | 4 | ( | x | − | 14 | ) | − | 3 | × | 5 | + | 48 |
| = | - | 12 | ( | x | − | 14 | ) | − | 15 | + | 48 |
| = | - | 12 | ( | x | − | 14 | ) | + | 33 |
| = | - | 12 | x | + | 12 | × | 14 | + | 33 |
| = | - | 12 | x | + | 168 | + | 33 |
| = | - | 12 | x | + | 201 |
| - | 12 | x | + | 201 | = | - | 3 | x | + | 120 |
| - | 12 | x | + | 3 | x | = | 120 | − | 201 |
| - | 9 | x | = | 120 | − | 201 |
| - | 9 | x | = | - | 81 |
| 81 | = | 9 | x |
| 9 | x | = | 81 |
| x | = | 81 | ÷ | 9 |
| = | 81 | × | 1 9 |
| = | 9 | × | 1 |
| x | = | 9 |