| 4 | ( | x | + | 5 | ) | + | 15 | ÷ | 4 | × | ( | x | + | 5 | ) | − | 15 | = | 0 |
| Left side of the equation = | 4 | ( | x | + | 5 | ) | + | 15 4 | ( | x | + | 5 | ) | − | 15 |
| 4 | ( | x | + | 5 | ) | + | 15 4 | ( | x | + | 5 | ) | − | 15 | = | 0 |
| Left side of the equation = | 4 | x | + | 4 | × | 5 | + | 15 4 | ( | x | + | 5 | ) | − | 15 |
| = | 4 | x | + | 20 | + | 15 4 | ( | x | + | 5 | ) | − | 15 |
| = | 4 | x | + | 5 | + | 15 4 | ( | x | + | 5 | ) |
| = | 4 | x | + | 5 | + | 15 4 | x | + | 15 4 | × | 5 |
| = | 4 | x | + | 5 | + | 15 4 | x | + | 75 4 |
| = | 31 4 | x | + | 95 4 |
31 4 | x | + | 95 4 | = | 0 |
31 4 | x | = | 0 | − | 95 4 |
31 4 | x | = | - | 95 4 |
| x | = | - | 95 4 | ÷ | 31 4 |
| = | - | 95 4 | × | 4 31 |
| = | - | 95 | × | 1 31 |
| x | = | - | 95 31 |
| x | = | - 3.064516 |