| 3000 | × | 30 | + | 50 | ( | x | − | 30 | ) | = | 90000 |
| Left side of the equation = | 90000 | + | 50 | ( | x | − | 30 | ) |
| 90000 | + | 50 | ( | x | − | 30 | ) | = | 90000 |
| Left side of the equation = | 90000 | + | 50 | x | − | 50 | × | 30 |
| = | 90000 | + | 50 | x | − | 1500 |
| = | 88500 | + | 50 | x |
| 88500 | + | 50 | x | = | 90000 |
| 50 | x | = | 90000 | − | 88500 |
| 50 | x | = | 1500 |
| x | = | 1500 | ÷ | 50 |
| = | 1500 | × | 1 50 |
| = | 30 | × | 1 |
| x | = | 30 |