| ( | 4 | − | x | ) | ( | 200 | + | 50 | x | ) | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) | = | 450 |
| Left side of the equation = | 4 | ( | 200 | + | 50 | x | ) | − | x | ( | 200 | + | 50 | x | ) | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) |
| = | 4 | × | 200 | + | 4 | × | 50 | x | − | x | ( | 200 | + | 50 | x | ) | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) |
| = | 800 | + | 200 | x | − | x | ( | 200 | + | 50 | x | ) | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) |
| = | 800 | + | 200 | x | − | x | × | 200 | − | x | × | 50 | x | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) |
| = | 800 | + | 0 | x | − | x | × | 50 | x | + | ( | - | 2 | ( | 200 | − | 50 | x | ) | ) |
| = | 800 | + | 0 | x | − | x | × | 50 | x | − | 2 | ( | 200 | − | 50 | x | ) |
| = | 800 | + | 0 | x | − | x | × | 50 | x | − | 2 | × | 200 | + | 2 | × | 50 | x |
| = | 800 | + | 0 | x | − | x | × | 50 | x | − | 400 | + | 100 | x |
| = | 400 | + | 100 | x | − | x | × | 50 | x |
| 400 | + | 100 | x | − | x | × | 50 | x | = | 450 |