| ( | x | − | 15 | ) | ÷ | ( | x | + | 85 | ) | = | x | ÷ | ( | x | + | 500 | ÷ | 3 | ) |
| 方程两边同时乘以: | ( | x | + | 85 | ) | , | ( | x | + | 500 | ÷ | 3 | ) |
| ( | x | − | 15 | ) | ( | x | + | 500 | ÷ | 3 | ) | = | x | ( | x | + | 85 | ) |
| x | ( | x | + | 500 | ÷ | 3 | ) | − | 15 | ( | x | + | 500 | ÷ | 3 | ) | = | x | ( | x | + | 85 | ) |
| x | ( | x | + | 500 | ÷ | 3 | ) | − | 15 | ( | x | + | 500 | ÷ | 3 | ) | = | x | x | + | x | × | 85 |
| x | x | + | x | × | 500 | ÷ | 3 | − | 15 | ( | x | + | 500 | ÷ | 3 | ) | = | x | x | + | 85 | x |
| x | x | + | x | × | 500 3 | − | 15 | ( | x | + | 500 | ÷ | 3 | ) | = | x | x | + | 85 | x |
| x | x | + | 500 3 | x | − | 15 | x | − | 15 | × | 500 | ÷ | 3 | = | x | x | + | 85 | x |
| x | x | + | 500 3 | x | − | 15 | x | − | 2500 | = | x | x | + | 85 | x |
| x | x | + | 455 3 | x | − | 2500 | = | x | x | + | 85 | x |
| x1= | 75 2 |