| 2 | ( | x | + | 121 5 | ) | = | 50 | + | 220 | − | 2 | x | + | 88 |
| 方程左边 = | 2 | x | + | 2 | × | 121 5 |
| = | 2 | x | + | 242 5 |
| 2 | x | + | 242 5 | = | 50 | + | 220 | − | 2 | x | + | 88 |
| 方程右边 = | 358 | − | 2 | x |
| 2 | x | + | 242 5 | = | 358 | − | 2 | x |
| 2 | x | + | 2 | x | = | 358 | − | 242 5 |
| 4 | x | = | 358 | − | 242 5 |
| 4 | x | = | 1548 5 |
| x | = | 1548 5 | ÷ | 4 |
| = | 1548 5 | × | 1 4 |
| = | 387 5 | × | 1 |
| x | = | 387 5 |
| x | = | 77.4 |