| ( | 56 | − | x | ) | − | ( | x | − | 28 | ) | = | 213 | ( | x | − | ( | x | − | 28 | ) | ) |
| Left side of the equation = | 56 | − | x | − | ( | x | − | 28 | ) |
| = | 56 | − | x | − | x | + | 28 |
| = | 84 | − | 2 | x |
| 84 | − | 2 | x | = | 213 | ( | x | − | ( | x | − | 28 | ) | ) |
| Right side of the equation = | 213 | x | − | 213 | ( | x | − | 28 | ) |
| = | 213 | x | − | 213 | x | + | 213 | × | 28 |
| = | 213 | x | − | 213 | x | + | 5964 |
| = | 0 | x | + | 5964 |
| 84 | − | 2 | x | = | 5964 |
| - | 2 | x | = | 5964 | − | 84 |
| - | 2 | x | = | 5880 |
| - | 5880 | = | 2 | x |
| 2 | x | = | - | 5880 |
| x | = | - | 5880 | ÷ | 2 |
| = | - | 5880 | × | 1 2 |
| = | - | 2940 | × | 1 |
| x | = | - | 2940 |