| ( | 100 | − | x | ) | × | 80 | = | ( | 95 | − | x | ) | × | 100 |
| Left side of the equation = | 100 | × | 80 | − | x | × | 80 |
| = | 8000 | − | x | × | 80 |
| 8000 | − | 80 | x | = | ( | 95 | − | x | ) | × | 100 |
| Right side of the equation = | 95 | × | 100 | − | x | × | 100 |
| = | 9500 | − | x | × | 100 |
| 8000 | − | 80 | x | = | 9500 | − | 100 | x |
| - | 80 | x | + | 100 | x | = | 9500 | − | 8000 |
| 20 | x | = | 9500 | − | 8000 |
| 20 | x | = | 1500 |
| x | = | 1500 | ÷ | 20 |
| = | 1500 | × | 1 20 |
| = | 75 | × | 1 |
| x | = | 75 |