| 52 | × | 28 | − | ( | 2 | × | 28 | x | + | 2 | ( | 52 | − | 2 | x | ) | x | ) | = | 640 |
| Left side of the equation = | 1456 | − | ( | 2 | × | 28 | x | + | 2 | ( | 52 | − | 2 | x | ) | x | ) |
| 1456 | − | ( | 2 | × | 28 | x | + | 2 | ( | 52 | − | 2 | x | ) | x | ) | = | 640 |
| Left side of the equation = | 1456 | − | 2 | × | 28 | x | − | 2 | ( | 52 | − | 2 | x | ) | x |
| = | 1456 | − | 56 | x | − | 2 | ( | 52 | − | 2 | x | ) | x |
| = | 1456 | − | 56 | x | − | 2 | × | 52 | x | + | 2 | × | 2 | x | x |
| = | 1456 | − | 56 | x | − | 104 | x | + | 4 | x | x |
| = | 1456 | − | 160 | x | + | 4 | x | x |
| 1456 | − | 160 | x | + | 4 | x | x | = | 640 |