| ( | 180 | + | x | − | 20 | ) | ( | 50 | − | x | ÷ | 10 | ) | = | 10890 |
| Left side of the equation = | 180 | ( | 50 | − | x | ÷ | 10 | ) | + | x | ( | 50 | − | x | ÷ | 10 | ) | − | 20 | ( | 50 | − | x | ÷ | 10 | ) |
| = | 180 | × | 50 | − | 180 | x | ÷ | 10 | + | x | ( | 50 | − | x | ÷ | 10 | ) | − | 20 | ( | 50 | − | x | ÷ | 10 | ) |
| = | 9000 | − | 18 | x | + | x | ( | 50 | − | x | ÷ | 10 | ) | − | 20 | ( | 50 | − | x | ÷ | 10 | ) |
| = | 9000 | − | 18 | x | + | x | × | 50 | − | x | x | ÷ | 10 | − | 20 | ( | 50 | − | x | ÷ | 10 | ) |
| = | 9000 | + | 32 | x | − | x | x | × | 1 10 | − | 20 | ( | 50 | − | x | ÷ | 10 | ) |
| = | 9000 | + | 32 | x | − | x | x | × | 1 10 | − | 20 | × | 50 | + | 20 | x | ÷ | 10 |
| = | 9000 | + | 32 | x | − | x | x | × | 1 10 | − | 1000 | + | 2 | x |
| = | 8000 | + | 34 | x | − | x | x | × | 1 10 |
| 8000 | + | 34 | x | − | x | x | × | 1 10 | = | 10890 |