| 50 | × | 80 | + | 100 | ( | 50 | − | x | ) | + | 100 | × | 9 10 | x | − | 6500 | = | 2250 |
| Left side of the equation = | 4000 | + | 100 | ( | 50 | − | x | ) | + | 90 | x | − | 6500 |
| = | - | 2500 | + | 100 | ( | 50 | − | x | ) | + | 90 | x |
| - | 2500 | + | 100 | ( | 50 | − | x | ) | + | 90 | x | = | 2250 |
| Left side of the equation = | - | 2500 | + | 100 | × | 50 | − | 100 | x | + | 90 | x |
| = | - | 2500 | + | 5000 | − | 100 | x | + | 90 | x |
| = | 2500 | − | 10 | x |
| 2500 | − | 10 | x | = | 2250 |
| - | 10 | x | = | 2250 | − | 2500 |
| - | 10 | x | = | - | 250 |
| 250 | = | 10 | x |
| 10 | x | = | 250 |
| x | = | 250 | ÷ | 10 |
| = | 250 | × | 1 10 |
| = | 25 | × | 1 |
| x | = | 25 |