| x | + | 2 | x | + | 3 | x | + | 4 | x | + | 5 | x | + | 6 | x | + | 7 | = | 2 | ( | x | + | 2 | x | + | 3 | x | + | 4 | x | + | 5 | x | + | 6 | x | + | 7 | ) |
| Left side of the equation = | 55 | x | + | 55 |
| 55 | x | + | 55 | = | 2 | ( | x | + | 2 | x | + | 3 | x | + | 4 | x | + | 5 | x | + | 6 | x | + | 7 | ) |
| Right side of the equation = | 2 | x | + | 2 | × | 2 | x | + | 2 | × | 3 | x | + | 2 | × | 4 | x | + | 2 |
| = | 2 | x | + | 4 | x | + | 6 | x | + | 8 | x | + | 10 | x | + | 12 | x |
| = | 110 | x |
| 55 | x | + | 55 | = | 110 | x |
| 55 | x | − | 110 | x | = | - | 55 |
| - | 55 | x | = | - | 55 |
| 55 | = | 55 | x |
| 55 | x | = | 55 |
| x | = | 55 | ÷ | 55 |
| = | 55 | × | 1 55 |
| = | 1 | × | 1 |
| x | = | 1 |