| ( | 40 | + | 40 | − | 1 2 | X | ) | ( | X | ÷ | 4 | ) | = | 200 |
| Left side of the equation = | 40 | ( | X | ÷ | 4 | ) | + | 40 | ( | X | ÷ | 4 | ) | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 40 | X | ÷ | 4 | + | 40 | ( | X | ÷ | 4 | ) | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 10 | X | + | 40 | ( | X | ÷ | 4 | ) | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 10 | X | + | 40 | X | ÷ | 4 | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 10 | X | + | 10 | X | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 20 | X | − | 1 2 | X | ( | X | ÷ | 4 | ) |
| = | 20 | X | − | 1 2 | X | X | ÷ | 4 |
| = | 20 | X | − | 1 8 | X | X |
| 20 | X | − | 1 8 | X | X | = | 200 |