| ( | ( | x | + | 160 | ) | + | x | + | ( | x | − | 20 | ) | ) | ÷ | 3 | = | 0 |
| 方程左边 = | ( | x | + | 160 | ) | × | 1 3 | + | x | × | 1 3 | + | ( | x | − | 20 | ) | × | 1 3 |
| = | x | × | 1 3 | + | 160 | × | 1 3 | + | 1 3 | x | + | ( | x | − | 20 | ) | × | 1 3 |
| = | x | × | 1 3 | + | 160 3 | + | 1 3 | x | + | ( | x | − | 20 | ) | × | 1 3 |
| = | 2 3 | x | + | 160 3 | + | ( | x | − | 20 | ) | × | 1 3 |
| = | 2 3 | x | + | 160 3 | + | x | × | 1 3 | − | 20 | × | 1 3 |
| = | 2 3 | x | + | 160 3 | + | x | × | 1 3 | − | 20 3 |
| = | 1 | x | + | 140 3 |
| 1 | x | + | 140 3 | = | 0 |
| 1 | x | = | 0 | − | 140 3 |
| x | = | 0 | − | 140 3 |
| x | = | - | 140 3 |