| ( | 200 | + | x | ) | ( | 50 | − | x | ÷ | 5 | ) | = | 10120 |
| Left side of the equation = | 200 | ( | 50 | − | x | ÷ | 5 | ) | + | x | ( | 50 | − | x | ÷ | 5 | ) |
| = | 200 | × | 50 | − | 200 | x | ÷ | 5 | + | x | ( | 50 | − | x | ÷ | 5 | ) |
| = | 10000 | − | 40 | x | + | x | ( | 50 | − | x | ÷ | 5 | ) |
| = | 10000 | − | 40 | x | + | x | × | 50 | − | x | x | ÷ | 5 |
| = | 10000 | + | 10 | x | − | x | x | × | 1 5 |
| 10000 | + | 10 | x | − | x | x | × | 1 5 | = | 10120 |