| 12 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | × | 9 | ÷ | 2 | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | ÷ | 2 | = | 36 |
| Left side of the equation = | 54 13 | ( | 13 | − | x | − | 4 | ) | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | × | 1 2 |
54 13 | ( | 13 | − | x | − | 4 | ) | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | × | 1 2 | = | 36 |
| Left side of the equation = | 54 13 | × | 13 | − | 54 13 | x | − | 54 13 | × | 4 | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | × | 1 2 |
| = | 54 | − | 54 13 | x | − | 216 13 | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | × | 1 2 |
| = | 486 13 | − | 54 13 | x | + | ( | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | + | 4 | ) | x | × | 1 2 |
| = | 486 13 | − | 54 13 | x | + | 5 | ( | 13 | − | x | − | 4 | ) | ÷ | 13 | × | x | × | 1 2 | + | 4 | x | × | 1 2 |
| = | 486 13 | − | 54 13 | x | + | 5 26 | ( | 13 | − | x | − | 4 | ) | x | + | 2 | x |
| = | 486 13 | − | 28 13 | x | + | 5 26 | ( | 13 | − | x | − | 4 | ) | x |
| = | 486 13 | − | 28 13 | x | + | 5 26 | × | 13 | x | − | 5 26 | x | x | − | 5 26 | × | 4 | x |
| = | 486 13 | − | 28 13 | x | + | 5 2 | x | − | 5 26 | x | x | − | 10 13 | x |
| = | 486 13 | − | 11 26 | x | − | 5 26 | x | x |
486 13 | − | 11 26 | x | − | 5 26 | x | x | = | 36 |
| x2= | 9 5 |