| ( | x | − | 6 | ) | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) | = | 6300 |
| Left side of the equation = | x | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) | − | 6 | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) |
| = | x | × | 300 | + | x | ( | 25 | − | x | ) | × | 30 | − | 6 | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) |
| = | 300 | x | + | x | × | 25 | × | 30 | − | x | x | × | 30 | − | 6 | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) |
| = | 300 | x | + | x | × | 750 | − | x | x | × | 30 | − | 6 | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) |
| = | 1050 | x | − | x | x | × | 30 | − | 6 | ( | 300 | + | ( | 25 | − | x | ) | × | 30 | ) |
| = | 1050 | x | − | x | x | × | 30 | − | 6 | × | 300 | − | 6 | ( | 25 | − | x | ) | × | 30 |
| = | 1050 | x | − | x | x | × | 30 | − | 1800 | − | 180 | ( | 25 | − | x | ) |
| = | 1050 | x | − | x | x | × | 30 | − | 1800 | − | 180 | × | 25 | + | 180 | x |
| = | 1050 | x | − | x | x | × | 30 | − | 1800 | − | 4500 | + | 180 | x |
| = | 1230 | x | − | x | x | × | 30 | − | 6300 |
| 1230 | x | − | x | x | × | 30 | − | 6300 | = | 6300 |