| 9 | x | × | 7 | x | = | ( | 1 | − | 17 | ÷ | 81 | ) | × | 27 | × | 21 |
| Left side of the equation = | 63 | x | x |
| 63 | x | x | = | ( | 1 | − | 17 | ÷ | 81 | ) | × | 27 | × | 21 |
| Right side of the equation = | ( | 1 | − | 17 | ÷ | 81 | ) | × | 567 |
| 63 | x | x | = | ( | 1 | − | 17 | ÷ | 81 | ) | × | 567 |
| Right side of the equation = | 1 | × | 567 | − | 17 | ÷ | 81 | × | 567 |
| = | 567 | − | 119 |
| = | 448 |
| 63 | x | x | = | 448 |
| x1= | - | 8 3 |
| x2= | 8 3 |