| ( | 10 | − | x | ) | ( | 200 | + | 50 | x | ) | + | 2000 | − | 200 | x | = | 1250 |
| Left side of the equation = | 10 | ( | 200 | + | 50 | x | ) | − | x | ( | 200 | + | 50 | x | ) | + | 2000 | − | 200 | x |
| = | 10 | × | 200 | + | 10 | × | 50 | x | − | x | ( | 200 | + | 50 | x | ) | + | 2000 | − | 200 | x |
| = | 2000 | + | 500 | x | − | x | ( | 200 | + | 50 | x | ) | + | 2000 | − | 200 | x |
| = | 4000 | + | 300 | x | − | x | ( | 200 | + | 50 | x | ) |
| = | 4000 | + | 300 | x | − | x | × | 200 | − | x | × | 50 | x |
| = | 4000 | + | 100 | x | − | x | × | 50 | x |
| 4000 | + | 100 | x | − | x | × | 50 | x | = | 1250 |