| 60 | ( | 5 | + | x | ) | = | 90 | ( | x | − | 4 | ) |
| Left side of the equation = | 60 | × | 5 | + | 60 | x |
| = | 300 | + | 60 | x |
| 300 | + | 60 | x | = | 90 | ( | x | − | 4 | ) |
| Right side of the equation = | 90 | x | − | 90 | × | 4 |
| = | 90 | x | − | 360 |
| 300 | + | 60 | x | = | 90 | x | − | 360 |
| 60 | x | − | 90 | x | = | - | 360 | − | 300 |
| - | 30 | x | = | - | 360 | − | 300 |
| - | 30 | x | = | - | 660 |
| 660 | = | 30 | x |
| 30 | x | = | 660 |
| x | = | 660 | ÷ | 30 |
| = | 660 | × | 1 30 |
| = | 22 | × | 1 |
| x | = | 22 |