| 200 | × | 40 | + | ( | 40 | − | x | ) | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) | = | 9200 |
| Left side of the equation = | 8000 | + | ( | 40 | − | x | ) | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| 8000 | + | ( | 40 | − | x | ) | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) | = | 9200 |
| Left side of the equation = | 8000 | + | 40 | ( | 200 | + | 2 | x | ) | − | x | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 8000 | + | 40 | × | 200 | + | 40 | × | 2 | x | − | x | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 8000 | + | 8000 | + | 80 | x | − | x | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 16000 | + | 80 | x | − | x | ( | 200 | + | 2 | x | ) | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 16000 | + | 80 | x | − | x | × | 200 | − | x | × | 2 | x | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 16000 | − | 120 | x | − | x | × | 2 | x | + | ( | 400 | − | 2 | x | ) | ( | 50 | − | 60 | ) |
| = | 16000 | − | 120 | x | − | x | × | 2 | x | + | 400 | ( | 50 | − | 60 | ) | − | 2 | x | ( | 50 | − | 60 | ) |
| = | 16000 | − | 120 | x | − | x | × | 2 | x | + | 400 | × | 50 | − | 400 | × | 60 | − | 2 | x |
| = | 16000 | − | 120 | x | − | x | × | 2 | x | + | 20000 | − | 24000 | − | 2 | x | ( | 50 | − | 60 | ) |
| = | 12000 | − | 120 | x | − | x | × | 2 | x | − | 2 | x | ( | 50 | − | 60 | ) |
| = | 12000 | − | 120 | x | − | x | × | 2 | x | − | 2 | x | × | 50 | + | 2 | x | × | 60 |
| = | 12000 | − | 120 | x | − | x | × | 2 | x | − | 100 | x | + | 120 | x |
| = | 12000 | − | 100 | x | − | x | × | 2 | x |
| 12000 | − | 100 | x | − | x | × | 2 | x | = | 9200 |