| ( | 16 | − | x | ) | ( | 40 | + | 10 | x | ) | = | 750 |
| Left side of the equation = | 16 | ( | 40 | + | 10 | x | ) | − | x | ( | 40 | + | 10 | x | ) |
| = | 16 | × | 40 | + | 16 | × | 10 | x | − | x | ( | 40 | + | 10 | x | ) |
| = | 640 | + | 160 | x | − | x | ( | 40 | + | 10 | x | ) |
| = | 640 | + | 160 | x | − | x | × | 40 | − | x | × | 10 | x |
| = | 640 | + | 120 | x | − | x | × | 10 | x |
| 640 | + | 120 | x | − | x | × | 10 | x | = | 750 |