| ( | 350 | − | x | ) | ( | 30 | + | x | ÷ | 5 | ) | = | 12000 |
| Left side of the equation = | 350 | ( | 30 | + | x | ÷ | 5 | ) | − | x | ( | 30 | + | x | ÷ | 5 | ) |
| = | 350 | × | 30 | + | 350 | x | ÷ | 5 | − | x | ( | 30 | + | x | ÷ | 5 | ) |
| = | 10500 | + | 70 | x | − | x | ( | 30 | + | x | ÷ | 5 | ) |
| = | 10500 | + | 70 | x | − | x | × | 30 | − | x | x | ÷ | 5 |
| = | 10500 | + | 40 | x | − | x | x | × | 1 5 |
| 10500 | + | 40 | x | − | x | x | × | 1 5 | = | 12000 |