| 40 | ( | 9 10 | x | − | x | ) | = | 60 | ( | 4 5 | x | − | x | ) |
| Left side of the equation = | 40 | × | 9 10 | x | − | 40 | x |
| = | 36 | x | − | 40 | x |
| = | - | 4 | x |
| - | 4 | x | = | 60 | ( | 4 5 | x | − | x | ) |
| Right side of the equation = | 60 | × | 4 5 | x | − | 60 | x |
| = | 48 | x | − | 60 | x |
| = | - | 12 | x |
| - | 4 | x | = | - | 12 | x |
| - | 4 | x | + | 12 | x | = | 0 |
| 8 | x | = | 0 |
| x | = | 0 | ÷ | 8 |
| = | 0 | × | 1 8 |
| x | = | 0 |