| ( | ( | 40 | − | x | ) | × | 12 | + | 576 | ) | ( | x | − | 30 | ) | = | 4800 |
| Left side of the equation = | ( | 40 | − | x | ) | × | 12 | ( | x | − | 30 | ) | + | 576 | ( | x | − | 30 | ) |
| = | 40 | × | 12 | ( | x | − | 30 | ) | − | x | × | 12 | ( | x | − | 30 | ) | + | 576 | ( | x | − | 30 | ) |
| = | 480 | ( | x | − | 30 | ) | − | x | × | 12 | ( | x | − | 30 | ) | + | 576 | ( | x | − | 30 | ) |
| = | 480 | x | − | 480 | × | 30 | − | x | × | 12 | ( | x | − | 30 | ) | + | 576 | ( | x | − | 30 | ) |
| = | 480 | x | − | 14400 | − | x | × | 12 | ( | x | − | 30 | ) | + | 576 | ( | x | − | 30 | ) |
| = | 480 | x | − | 14400 | − | x | × | 12 | x | + | x | × | 12 | × | 30 | + | 576 | ( | x | − | 30 | ) |
| = | 480 | x | − | 14400 | − | x | × | 12 | x | + | x | × | 360 | + | 576 | ( | x | − | 30 | ) |
| = | 840 | x | − | 14400 | − | x | × | 12 | x | + | 576 | ( | x | − | 30 | ) |
| = | 840 | x | − | 14400 | − | x | × | 12 | x | + | 576 | x | − | 576 | × | 30 |
| = | 840 | x | − | 14400 | − | x | × | 12 | x | + | 576 | x | − | 17280 |
| = | 1416 | x | − | 31680 | − | x | × | 12 | x |
| 1416 | x | − | 31680 | − | x | × | 12 | x | = | 4800 |