| 0 | = | ( | 12 | − | x | ) | ( | 40 | + | 2 | x | ) | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| Right side of the equation = | 12 | ( | 40 | + | 2 | x | ) | − | x | ( | 40 | + | 2 | x | ) | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| = | 12 | × | 40 | + | 12 | × | 2 | x | − | x | ( | 40 | + | 2 | x | ) | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| = | 480 | + | 24 | x | − | x | ( | 40 | + | 2 | x | ) | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| = | 480 | + | 24 | x | − | x | × | 40 | − | x | × | 2 | x | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| = | 480 | − | 16 | x | − | x | × | 2 | x | + | ( | 8 | + | x | ) | ( | 80 | − | 2 | x | ) |
| = | 480 | − | 16 | x | − | x | × | 2 | x | + | 8 | ( | 80 | − | 2 | x | ) | + | x | ( | 80 | − | 2 | x | ) |
| = | 480 | − | 16 | x | − | x | × | 2 | x | + | 8 | × | 80 | − | 8 | × | 2 | x | + | x |
| = | 480 | − | 16 | x | − | x | × | 2 | x | + | 640 | − | 16 | x | + | x | ( | 80 | − | 2 | x | ) |
| = | 1120 | − | 32 | x | − | x | × | 2 | x | + | x | ( | 80 | − | 2 | x | ) |
| = | 1120 | − | 32 | x | − | x | × | 2 | x | + | x | × | 80 | − | x | × | 2 | x |
| = | 1120 | + | 48 | x | − | x | × | 2 | x | − | x | × | 2 | x |
| 0 | = | 1120 | + | 48 | x | − | x | × | 2 | x | − | x | × | 2 | x |