| 5 | ( | 2 | x | + | 1 | ) | = | 7 | ( | 3 | x | − | 4 | ) |
| Left side of the equation = | 5 | × | 2 | x | + | 5 | × | 1 |
| = | 10 | x | + | 5 |
| 10 | x | + | 5 | = | 7 | ( | 3 | x | − | 4 | ) |
| Right side of the equation = | 7 | × | 3 | x | − | 7 | × | 4 |
| = | 21 | x | − | 28 |
| 10 | x | + | 5 | = | 21 | x | − | 28 |
| 10 | x | − | 21 | x | = | - | 28 | − | 5 |
| - | 11 | x | = | - | 28 | − | 5 |
| - | 11 | x | = | - | 33 |
| 33 | = | 11 | x |
| 11 | x | = | 33 |
| x | = | 33 | ÷ | 11 |
| = | 33 | × | 1 11 |
| = | 3 | × | 1 |
| x | = | 3 |