| ( | 320 | + | 39 50 | X | ) | ÷ | 2 | = | 19 20 |
| 方程左边 = | 320 | × | 1 2 | + | 39 50 | X | × | 1 2 |
| = | 160 | + | 39 100 | X |
| 160 | + | 39 100 | X | = | 19 20 |
39 100 | X | = | 19 20 | − | 160 |
39 100 | X | = | - | 3181 20 |
| X | = | - | 3181 20 | ÷ | 39 100 |
| = | - | 3181 20 | × | 100 39 |
| = | - | 3181 | × | 5 39 |
| X | = | - | 15905 39 |
| X | = | - 407.820513 |
| 320 | + | 39 50 | X | = | 19 10 | ( | 320 | + | X | ) |
| 方程右边 = | 19 10 | × | 320 | + | 19 10 | X |
| = | 608 | + | 19 10 | X |
| 320 | + | 39 50 | X | = | 608 | + | 19 10 | X |
39 50 | X | − | 19 10 | X | = | 608 | − | 320 |
| - | 28 25 | X | = | 608 | − | 320 |
| - | 28 25 | X | = | 288 |
| - | 288 | = | 28 25 | X |
28 25 | X | = | - | 288 |
| X | = | - | 288 | ÷ | 28 25 |
| = | - | 288 | × | 25 28 |
| = | - | 72 | × | 25 7 |
| X | = | - | 1800 7 |
| X | = | - 257.142857 |
| 320 | + | 39 50 | X | + | 320 | × | 19 10 | + | 19 10 | X | = | 0 |
| 方程左边 = | 320 | + | 39 50 | X | + | 608 | + | 19 10 | X |
| = | 928 | + | 67 25 | X |
| 928 | + | 67 25 | X | = | 0 |
67 25 | X | = | 0 | − | 928 |
67 25 | X | = | - | 928 |
| X | = | - | 928 | ÷ | 67 25 |
| = | - | 928 | × | 25 67 |
| X | = | - | 23200 67 |
| X | = | - 346.268657 |
| 320 | + | 39 50 | X | = | 608 | + | 19 10 | X |
39 50 | X | − | 19 10 | X | = | 608 | − | 320 |
| - | 28 25 | X | = | 608 | − | 320 |
| - | 28 25 | X | = | 288 |
| - | 288 | = | 28 25 | X |
28 25 | X | = | - | 288 |
| X | = | - | 288 | ÷ | 28 25 |
| = | - | 288 | × | 25 28 |
| = | - | 72 | × | 25 7 |
| X | = | - | 1800 7 |
| X | = | - 257.142857 |