| ( | 68 | + | 90 | + | 92 | + | x | ) | ÷ | 4 | = | ( | 80 | + | x | ) | ÷ | 2 |
| 方程左边 = | 68 | × | 1 4 | + | 90 | × | 1 4 | + | 92 | × | 1 4 | + | x | × | 1 4 |
| = | 17 | + | 45 2 | + | 23 | + | x | × | 1 4 |
| = | 125 2 | + | 1 4 | x |
125 2 | + | 1 4 | x | = | ( | 80 | + | x | ) | ÷ | 2 |
| 方程右边 = | 80 | × | 1 2 | + | x | × | 1 2 |
| = | 40 | + | x | × | 1 2 |
125 2 | + | 1 4 | x | = | 40 | + | 1 2 | x |
1 4 | x | − | 1 2 | x | = | 40 | − | 125 2 |
| - | 1 4 | x | = | 40 | − | 125 2 |
| - | 1 4 | x | = | - | 45 2 |
45 2 | = | 1 4 | x |
1 4 | x | = | 45 2 |
| x | = | 45 2 | ÷ | 1 4 |
| = | 45 2 | × | 4 |
| = | 45 | × | 2 |
| x | = | 90 |