| ( | 8 5 | − | x | ) | ( | 400 | + | 400 | x | ) | = | ( | 3200 | + | 2000 | x | ) | ( | 2 5 | − | x | ) | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| Left side of the equation = | 8 5 | ( | 400 | + | 400 | x | ) | − | x | ( | 400 | + | 400 | x | ) |
| = | 8 5 | × | 400 | + | 8 5 | × | 400 | x | − | x | ( | 400 | + | 400 | x | ) |
| = | 640 | + | 640 | x | − | x | ( | 400 | + | 400 | x | ) |
| = | 640 | + | 640 | x | − | x | × | 400 | − | x | × | 400 | x |
| = | 640 | + | 240 | x | − | x | × | 400 | x |
| 640 | + | 240 | x | − | x | × | 400 | x | = | ( | 3200 | + | 2000 | x | ) | ( | 2 5 | − | x | ) | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| Right side of the equation = | 3200 | ( | 2 5 | − | x | ) | + | 2000 | x | ( | 2 5 | − | x | ) | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 3200 | × | 2 5 | − | 3200 | x | + | 2000 | x | ( | 2 5 | − | x | ) | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 1280 | − | 3200 | x | + | 2000 | x | ( | 2 5 | − | x | ) | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 1280 | − | 3200 | x | + | 2000 | x | × | 2 5 | − | 2000 | x | x | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 1280 | − | 3200 | x | + | 800 | x | − | 2000 | x | x | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 1280 | − | 2400 | x | − | 2000 | x | x | − | 1600 | ( | 2 5 | − | x | ) | ( | 8 5 | − | x | ) |
| = | 1280 | − | 2400 | x | − | 2000 | x | x | − | 1600 | × | 2 5 | ( | 8 5 | − | x | ) | + | 1600 | x | ( | 8 5 | − | x | ) |
| = | 1280 | − | 2400 | x | − | 2000 | x | x | − | 640 | ( | 8 5 | − | x | ) | + | 1600 | x | ( | 8 5 | − | x | ) |
| = | 1280 | − | 2400 | x | − | 2000 | x | x | − | 640 | × | 8 5 | + | 640 | x | + | 1600 | x |
| = | 1280 | − | 2400 | x | − | 2000 | x | x | − | 1024 | + | 640 | x | + | 1600 | x | ( | 8 5 | − | x | ) |
| = | 256 | − | 1760 | x | − | 2000 | x | x | + | 1600 | x | ( | 8 5 | − | x | ) |
| = | 256 | − | 1760 | x | − | 2000 | x | x | + | 1600 | x | × | 8 5 | − | 1600 | x | x |
| = | 256 | − | 1760 | x | − | 2000 | x | x | + | 2560 | x | − | 1600 | x | x |
| = | 256 | + | 800 | x | − | 2000 | x | x | − | 1600 | x | x |
| 640 | + | 240 | x | − | x | × | 400 | x | = | 256 | + | 800 | x | − | 2000 | x | x | − | 1600 | x | x |