1 20 | = | ( | 2 | + | ( | 4 | ÷ | 69 | + | X | ) | × | 50 | ) | ÷ | ( | 90 | + | 90 | X | ) |
| 方程两边同时乘以: | ( | 90 | + | 90 | X | ) |
1 20 | ( | 90 | + | 90 | X | ) | = | ( | 2 | + | ( | 4 | ÷ | 69 | + | X | ) | × | 50 | ) |
1 20 | × | 90 | + | 1 20 | × | 90 | X | = | ( | 2 | + | ( | 4 | ÷ | 69 | + | X | ) | × | 50 | ) |
1 20 | × | 90 | + | 1 20 | × | 90 | X | = | 2 | + | ( | 4 | ÷ | 69 | + | X | ) | × | 50 |
9 2 | + | 9 2 | X | = | 2 | + | ( | 4 | ÷ | 69 | + | X | ) | × | 50 |
9 2 | + | 9 2 | X | = | 2 | + | 4 | ÷ | 69 | × | 50 | + | X | × | 50 |
9 2 | + | 9 2 | X | = | 2 | + | 200 69 | + | X | × | 50 |
9 2 | + | 9 2 | X | = | 338 69 | + | 50 | X |
9 2 | X | − | 50 | X | = | 338 69 | − | 9 2 |
| - | 91 2 | X | = | 338 69 | − | 9 2 |
| - | 91 2 | X | = | 55 138 |
| - | 55 138 | = | 91 2 | X |
91 2 | X | = | - | 55 138 |
| X | = | - | 55 138 | ÷ | 91 2 |
| = | - | 55 138 | × | 2 91 |
| = | - | 55 69 | × | 1 91 |
| X | = | - | 55 6279 |
| X | = | - 0.008759 |