| ( | 287 5 | × | 300 | + | 0 | ) | ÷ | ( | 100 | + | x | ) | = | 13 |
| 方程两边同时乘以: | ( | 100 | + | x | ) |
| ( | 287 5 | × | 300 | + | 0 | ) | = | 13 | ( | 100 | + | x | ) |
287 5 | × | 300 | + | 0 | = | 13 | ( | 100 | + | x | ) |
287 5 | × | 300 | + | 0 | = | 13 | × | 100 | + | 13 | x |
| 17220 | + | 0 | = | 1300 | + | 13 | x |
| 17220 | = | 1300 | + | 13 | x |
| - | 13 | x | = | 1300 | − | 17220 |
| - | 13 | x | = | - | 15920 |
| 15920 | = | 13 | x |
| 13 | x | = | 15920 |
| x | = | 15920 | ÷ | 13 |
| = | 15920 | × | 1 13 |
| x | = | 15920 13 |
| x | = | 1224.615385 |