| 300 | + | ( | x | − | 300 | ) | × | 85 100 | = | ( | x | − | 200 | ) | × | 90 100 | + | 200 |
| Left side of the equation = | 300 | + | x | × | 85 100 | − | 300 | × | 85 100 |
| = | 300 | + | x | × | 85 100 | − | 255 |
| = | 45 | + | 85 100 | x |
| 45 | + | 85 100 | x | = | ( | x | − | 200 | ) | × | 90 100 | + | 200 |
| Right side of the equation = | x | × | 90 100 | − | 200 | × | 90 100 | + | 200 |
| = | x | × | 90 100 | − | 180 | + | 200 |
| = | 90 100 | x | + | 20 |
| 45 | + | 85 100 | x | = | 90 100 | x | + | 20 |
85 100 | x | − | 90 100 | x | = | 20 | − | 45 |
| - | 1 20 | x | = | 20 | − | 45 |
| - | 1 20 | x | = | - | 25 |
| 25 | = | 1 20 | x |
1 20 | x | = | 25 |
| x | = | 25 | ÷ | 1 20 |
| = | 25 | × | 20 |
| x | = | 500 |