| 5 | + | 8 | ( | 15 | − | ( | 5 | + | x | ) | ) | = | 5 | ( | x | + | 4 | ) |
| Left side of the equation = | 5 | + | 8 | × | 15 | − | 8 | ( | 5 | + | x | ) |
| = | 5 | + | 120 | − | 8 | ( | 5 | + | x | ) |
| = | 125 | − | 8 | ( | 5 | + | x | ) |
| = | 125 | − | 8 | × | 5 | − | 8 | x |
| = | 125 | − | 40 | − | 8 | x |
| = | 85 | − | 8 | x |
| 85 | − | 8 | x | = | 5 | ( | x | + | 4 | ) |
| Right side of the equation = | 5 | x | + | 5 | × | 4 |
| = | 5 | x | + | 20 |
| 85 | − | 8 | x | = | 5 | x | + | 20 |
| - | 8 | x | − | 5 | x | = | 20 | − | 85 |
| - | 13 | x | = | 20 | − | 85 |
| - | 13 | x | = | - | 65 |
| 65 | = | 13 | x |
| 13 | x | = | 65 |
| x | = | 65 | ÷ | 13 |
| = | 65 | × | 1 13 |
| = | 5 | × | 1 |
| x | = | 5 |