| ( | 5 | ( | 509 | + | X | ) | + | 116 | + | 75 | + | 20 | + | 31 | ) | ÷ | ( | 509 | + | 28 | + | 25 | + | 10 | + | 31 | + | X | ) | = | 47 10 |
| 方程两边同时乘以: | ( | 509 | + | 28 | + | 25 | + | 10 | + | 31 | + | X | ) |
| ( | 5 | ( | 509 | + | X | ) | + | 116 | + | 75 | + | 20 | + | 31 | ) | = | 47 10 | ( | 509 | + | 28 | + | 25 | + | 10 | + | 31 | + | X | ) |
| 5 | ( | 509 | + | X | ) | + | 116 | + | 75 | + | 20 | + | 31 | = | 47 10 | ( | 509 | + | 28 | + | 25 | + | 10 | + | 31 | + | X | ) |
| 5 | ( | 509 | + | X | ) | + | 116 | + | 75 | + | 20 | + | 31 | = | 47 10 | × | 509 | + | 47 10 | × | 28 | + | 47 10 | × | 25 | + | 47 10 | × | 10 | + | 47 10 | × | 31 | + | 47 10 | X |
| 5 | ( | 509 | + | X | ) | + | 116 | + | 75 | + | 20 | + | 31 | = | 23923 10 | + | 658 5 | + | 235 2 | + | 47 | + | 1457 10 | + | 47 10 | X |
| 5 | ( | 509 | + | X | ) | + | 242 | = | 28341 10 | + | 47 10 | X |
| 5 | × | 509 | + | 5 | X | + | 242 | = | 28341 10 | + | 47 10 | X |
| 2545 | + | 5 | X | + | 242 | = | 28341 10 | + | 47 10 | X |
| 2787 | + | 5 | X | = | 28341 10 | + | 47 10 | X |
| 5 | X | − | 47 10 | X | = | 28341 10 | − | 2787 |
3 10 | X | = | 28341 10 | − | 2787 |
3 10 | X | = | 471 10 |
| X | = | 471 10 | ÷ | 3 10 |
| = | 471 10 | × | 10 3 |
| = | 157 | × | 1 |
| X | = | 157 |