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 | + | X | ) | × | 50 |
9 2 | + | 9 2 | X | = | 2 | + | 200 | ÷ | ( | 69 | + | X | ) |
| 方程两边同时乘以: | ( | 69 | + | X | ) |
9 2 | ( | 69 | + | X | ) | + | 9 2 | X | ( | 69 | + | X | ) | = | 2 | ( | 69 | + | X | ) | + | 200 |
9 2 | × | 69 | + | 9 2 | X | + | 9 2 | X | ( | 69 | + | X | ) | = | 2 | ( | 69 | + | X | ) | + | 200 |
9 2 | × | 69 | + | 9 2 | X | + | 9 2 | X | ( | 69 | + | X | ) | = | 2 | × | 69 | + | 2 | X | + | 200 |
621 2 | + | 9 2 | X | + | 9 2 | X | ( | 69 | + | X | ) | = | 138 | + | 2 | X | + | 200 |
621 2 | + | 9 2 | X | + | 9 2 | X | ( | 69 | + | X | ) | = | 338 | + | 2 | X |
621 2 | + | 9 2 | X | + | 9 2 | X | × | 69 | + | 9 2 | X | X | = | 338 | + | 2 | X |
621 2 | + | 9 2 | X | + | 621 2 | X | + | 9 2 | X | X | = | 338 | + | 2 | X |
621 2 | + | 315 | X | + | 9 2 | X | X | = | 338 | + | 2 | X |