| ( | 180 | − | x | ) | + | 10 | = | ( | 90 | − | x | ) | × | 3 |
| Left side of the equation = | 180 | − | x | + | 10 |
| = | 190 | − | x |
| 190 | − | x | = | ( | 90 | − | x | ) | × | 3 |
| Right side of the equation = | 90 | × | 3 | − | x | × | 3 |
| = | 270 | − | x | × | 3 |
| 190 | − | x | = | 270 | − | 3 | x |
| - | x | + | 3 | x | = | 270 | − | 190 |
| 2 | x | = | 270 | − | 190 |
| 2 | x | = | 80 |
| x | = | 80 | ÷ | 2 |
| = | 80 | × | 1 2 |
| = | 40 | × | 1 |
| x | = | 40 |