| 3 | ( | x | + | 4 | ) | + | 15 | = | 15 | x | − | 5 | ( | x | − | 5 | ) |
| Left side of the equation = | 3 | x | + | 3 | × | 4 | + | 15 |
| = | 3 | x | + | 12 | + | 15 |
| = | 3 | x | + | 27 |
| 3 | x | + | 27 | = | 15 | x | − | 5 | ( | x | − | 5 | ) |
| Right side of the equation = | 15 | x | − | 5 | x | + | 5 | × | 5 |
| = | 15 | x | − | 5 | x | + | 25 |
| = | 10 | x | + | 25 |
| 3 | x | + | 27 | = | 10 | x | + | 25 |
| 3 | x | − | 10 | x | = | 25 | − | 27 |
| - | 7 | x | = | 25 | − | 27 |
| - | 7 | x | = | - | 2 |
| 2 | = | 7 | x |
| 7 | x | = | 2 |
| x | = | 2 | ÷ | 7 |
| = | 2 | × | 1 7 |
| x | = | 2 7 |
| x | = | 0.285714 |