| ( | 30 | x | ÷ | 120 | ) | − | ( | 30 | x | ÷ | 150 | ) | = | ( | 450 | ÷ | 1800 | ) |
| Left side of the equation = | 30 | x | ÷ | 120 | − | ( | 30 | x | ÷ | 150 | ) |
| = | 1 4 | x | − | ( | 30 | x | ÷ | 150 | ) |
| = | 1 4 | x | − | 30 | x | ÷ | 150 |
| = | 1 4 | x | − | 1 5 | x |
| = | 1 20 | x |
1 20 | x | = | ( | 450 | ÷ | 1800 | ) |
| Right side of the equation = | 450 | ÷ | 1800 |
| = | 1 4 |
1 20 | x | = | 1 4 |
| x | = | 1 4 | ÷ | 1 20 |
| = | 1 4 | × | 20 |
| = | 1 | × | 5 |
| x | = | 5 |