| 180 | ÷ | ( | 1800 | + | x | ) | × | 900 | = | 180 | − | x |
| Multiply both sides of the equation by: | ( | 1800 | + | x | ) |
| 180 | × | 900 | = | 180 | ( | 1800 | + | x | ) | − | x | ( | 1800 | + | x | ) |
| 180 | × | 900 | = | 180 | × | 1800 | + | 180 | x | − | x | ( | 1800 | + | x | ) |
| 162000 | = | 324000 | + | 180 | x | − | x | ( | 1800 | + | x | ) |
| 162000 | = | 324000 | + | 180 | x | − | x | × | 1800 | − | x | x |
| 162000 | = | 324000 | − | 1620 | x | − | x | x |