| ( | 6 | − | x | ) | ( | 150 | + | 50 | x | ) | = | 1000 |
| Left side of the equation = | 6 | ( | 150 | + | 50 | x | ) | − | x | ( | 150 | + | 50 | x | ) |
| = | 6 | × | 150 | + | 6 | × | 50 | x | − | x | ( | 150 | + | 50 | x | ) |
| = | 900 | + | 300 | x | − | x | ( | 150 | + | 50 | x | ) |
| = | 900 | + | 300 | x | − | x | × | 150 | − | x | × | 50 | x |
| = | 900 | + | 150 | x | − | x | × | 50 | x |
| 900 | + | 150 | x | − | x | × | 50 | x | = | 1000 |