| 5 | ( | - | 5 | x | + | 1 | ) | + | 5 | ( | 4 | x | − | 5 | ) | + | 10 | = | 5 |
| Left side of the equation = | - | 5 | × | 5 | x | + | 5 | × | 1 | + | 5 | ( | 4 | x | − | 5 | ) | + | 10 |
| = | - | 25 | x | + | 5 | + | 5 | ( | 4 | x | − | 5 | ) | + | 10 |
| = | - | 25 | x | + | 15 | + | 5 | ( | 4 | x | − | 5 | ) |
| = | - | 25 | x | + | 15 | + | 5 | × | 4 | x | − | 5 | × | 5 |
| = | - | 25 | x | + | 15 | + | 20 | x | − | 25 |
| = | - | 5 | x | − | 10 |
| - | 5 | x | − | 10 | = | 5 |
| - | 5 | x | = | 5 | + | 10 |
| - | 5 | x | = | 15 |
| - | 15 | = | 5 | x |
| 5 | x | = | - | 15 |
| x | = | - | 15 | ÷ | 5 |
| = | - | 15 | × | 1 5 |
| = | - | 3 | × | 1 |
| x | = | - | 3 |