| ( | 6 | + | x | ) | ( | 6 | + | x | ) | + | 81 | = | ( | 15 | − | x | ) | ( | 15 | − | x | ) |
| Left side of the equation = | 6 | ( | 6 | + | x | ) | + | x | ( | 6 | + | x | ) | + | 81 |
| = | 6 | × | 6 | + | 6 | x | + | x | ( | 6 | + | x | ) | + | 81 |
| = | 36 | + | 6 | x | + | x | ( | 6 | + | x | ) | + | 81 |
| = | 117 | + | 6 | x | + | x | ( | 6 | + | x | ) |
| = | 117 | + | 6 | x | + | x | × | 6 | + | x | x |
| = | 117 | + | 12 | x | + | x | x |
| 117 | + | 12 | x | + | x | x | = | ( | 15 | − | x | ) | ( | 15 | − | x | ) |
| Right side of the equation = | 15 | ( | 15 | − | x | ) | − | x | ( | 15 | − | x | ) |
| = | 15 | × | 15 | − | 15 | x | − | x | ( | 15 | − | x | ) |
| = | 225 | − | 15 | x | − | x | ( | 15 | − | x | ) |
| = | 225 | − | 15 | x | − | x | × | 15 | + | x | x |
| = | 225 | − | 30 | x | + | x | x |
| 117 | + | 12 | x | + | x | x | = | 225 | − | 30 | x | + | x | x |
| x= | 18 7 |