| 4 | x | ÷ | 80 | + | 4 | ( | x | + | 3 | ) | ÷ | 80 | = | 3 | ÷ | 4 |
| 方程左边 = | 1 20 | x | + | 1 20 | ( | x | + | 3 | ) |
1 20 | x | + | 1 20 | ( | x | + | 3 | ) | = | 3 | ÷ | 4 |
| 方程左边 = | 1 20 | x | + | 1 20 | x | + | 1 20 | × | 3 |
| = | 1 20 | x | + | 1 20 | x | + | 3 20 |
| = | 1 10 | x | + | 3 20 |
1 10 | x | + | 3 20 | = | 3 | ÷ | 4 |
| 方程右边 = | 3 4 |
1 10 | x | + | 3 20 | = | 3 4 |
1 10 | x | = | 3 4 | − | 3 20 |
1 10 | x | = | 3 5 |
| x | = | 3 5 | ÷ | 1 10 |
| = | 3 5 | × | 10 |
| = | 3 | × | 2 |
| x | = | 6 |