| 50 | × | 18 100 | = | ( | 50 | + | x | ) | × | 9 5 |
| Left side of the equation = | 9 |
| 9 | = | ( | 50 | + | x | ) | × | 9 5 |
| Right side of the equation = | 50 | × | 9 5 | + | x | × | 9 5 |
| = | 90 | + | x | × | 9 5 |
| 9 | = | 90 | + | 9 5 | x |
| - | 9 5 | x | = | 90 | − | 9 |
| - | 9 5 | x | = | 81 |
| - | 81 | = | 9 5 | x |
9 5 | x | = | - | 81 |
| x | = | - | 81 | ÷ | 9 5 |
| = | - | 81 | × | 5 9 |
| = | - | 9 | × | 5 |
| x | = | - | 45 |