| 2 | ( | - | x | + | 5 | ) | + | 8 | ( | x | + | 7 | ) | = | 5 | ( | x | + | 5 | ) | + | 39 |
| Left side of the equation = | - | 2 | x | + | 2 | × | 5 | + | 8 | ( | x | + | 7 | ) |
| = | - | 2 | x | + | 10 | + | 8 | ( | x | + | 7 | ) |
| = | - | 2 | x | + | 10 | + | 8 | x | + | 8 | × | 7 |
| = | - | 2 | x | + | 10 | + | 8 | x | + | 56 |
| = | 6 | x | + | 66 |
| 6 | x | + | 66 | = | 5 | ( | x | + | 5 | ) | + | 39 |
| Right side of the equation = | 5 | x | + | 5 | × | 5 | + | 39 |
| = | 5 | x | + | 25 | + | 39 |
| = | 5 | x | + | 64 |
| 6 | x | + | 66 | = | 5 | x | + | 64 |
| 6 | x | − | 5 | x | = | 64 | − | 66 |
| x | = | 64 | − | 66 |
| x | = | 64 | − | 66 |
| x | = | - | 2 |