| ( | 180 | − | x | ) | × | 3 | ÷ | 5 | = | 90 | − | x |
| Left side of the equation = | ( | 180 | − | x | ) | × | 3 5 |
| ( | 180 | − | x | ) | × | 3 5 | = | 90 | − | x |
| Left side of the equation = | 180 | × | 3 5 | − | x | × | 3 5 |
| = | 108 | − | x | × | 3 5 |
| 108 | − | 3 5 | x | = | 90 | − | x |
| - | 3 5 | x | + | x | = | 90 | − | 108 |
| - | - | 2 5 | x | = | 90 | − | 108 |
| - | - | 2 5 | x | = | - | 18 |
| 18 | = | - | 2 5 | x |
| - | 2 5 | x | = | 18 |
| x | = | -18 | ÷ | 2 5 |
| = | -18 | × | 5 2 |
| x | = | - | 90 2 |
| x | = | - | 45 |