| ( | 40 | + | 40 | + | 1 2 | ( | X | − | 1 | ) | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | = | 200 |
| Left side of the equation = | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | ( | X | − | 1 | ) | ÷ | 2 | + | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | ( | X | − | 1 | ) | + | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | × | 1 | + | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | + | 40 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | + | 40 | ( | X | − | 1 | ) | ÷ | 2 | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | + | 20 | ( | X | − | 1 | ) | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | + | 20 | X | − | 20 | × | 1 | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 20 | X | − | 20 | + | 20 | X | − | 20 | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 2 | ( | X | − | 1 | ) | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 2 | X | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | − | 1 2 | × | 1 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 2 | X | ( | ( | X | − | 1 | ) | ÷ | 2 | ) | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 2 | X | ( | X | − | 1 | ) | ÷ | 2 | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 4 | X | ( | X | − | 1 | ) | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 4 | X | X | − | 1 4 | X | × | 1 | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 40 | X | − | 40 | + | 1 4 | X | X | − | 1 4 | X | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 159 4 | X | − | 40 | + | 1 4 | X | X | − | 1 2 | ( | ( | X | − | 1 | ) | ÷ | 2 | ) |
| = | 159 4 | X | − | 40 | + | 1 4 | X | X | − | 1 2 | ( | X | − | 1 | ) | ÷ | 2 |
| = | 159 4 | X | − | 40 | + | 1 4 | X | X | − | 1 4 | ( | X | − | 1 | ) |
| = | 159 4 | X | − | 40 | + | 1 4 | X | X | − | 1 4 | X | + | 1 4 | × | 1 |
| = | 159 4 | X | − | 40 | + | 1 4 | X | X | − | 1 4 | X | + | 1 4 |
| = | 79 2 | X | − | 159 4 | + | 1 4 | X | X |
79 2 | X | − | 159 4 | + | 1 4 | X | X | = | 200 |