| ( | 8 | + | 2 | x | ) | ( | 80 | − | 4 | x | ) | = | 1080 |
| Left side of the equation = | 8 | ( | 80 | − | 4 | x | ) | + | 2 | x | ( | 80 | − | 4 | x | ) |
| = | 8 | × | 80 | − | 8 | × | 4 | x | + | 2 | x | ( | 80 | − | 4 | x | ) |
| = | 640 | − | 32 | x | + | 2 | x | ( | 80 | − | 4 | x | ) |
| = | 640 | − | 32 | x | + | 2 | x | × | 80 | − | 2 | x | × | 4 | x |
| = | 640 | − | 32 | x | + | 160 | x | − | 8 | x | x |
| = | 640 | + | 128 | x | − | 8 | x | x |
| 640 | + | 128 | x | − | 8 | x | x | = | 1080 |