| ( | 150 | − | 60 | ) | X | = | ( | 150 | + | 60 | ) | ( | 10 | + | X | ) |
| Left side of the equation = | 150 | X | − | 60 | X |
| = | 90 | X |
| 90 | X | = | ( | 150 | + | 60 | ) | ( | 10 | + | X | ) |
| Right side of the equation = | 150 | ( | 10 | + | X | ) | + | 60 | ( | 10 | + | X | ) |
| = | 150 | × | 10 | + | 150 | X | + | 60 | ( | 10 | + | X | ) |
| = | 1500 | + | 150 | X | + | 60 | ( | 10 | + | X | ) |
| = | 1500 | + | 150 | X | + | 60 | × | 10 | + | 60 | X |
| = | 1500 | + | 150 | X | + | 600 | + | 60 | X |
| = | 2100 | + | 210 | X |
| 90 | X | = | 2100 | + | 210 | X |
| 90 | X | − | 210 | X | = | 2100 |
| - | 120 | X | = | 2100 |
| - | 2100 | = | 120 | X |
| 120 | X | = | - | 2100 |
| X | = | - | 2100 | ÷ | 120 |
| = | - | 2100 | × | 1 120 |
| = | - | 35 | × | 1 2 |
| X | = | - | 35 2 |
| X | = | - 17.5 |