| ( | 30 | + | x | ) | ÷ | ( | 6 | x | ) | = | ( | 6 | x | ) | ÷ | ( | 30 | − | 3 | x | ) |
| 方程两边同时乘以: | ( | 6 | x | ) | , | ( | 30 | − | 3 | x | ) |
| ( | 30 | + | x | ) | ( | 30 | − | 3 | x | ) | = | ( | 6 | x | ) | ( | 6 | x | ) |
| 30 | ( | 30 | − | 3 | x | ) | + | x | ( | 30 | − | 3 | x | ) | = | ( | 6 | x | ) | ( | 6 | x | ) |
| 30 | ( | 30 | − | 3 | x | ) | + | x | ( | 30 | − | 3 | x | ) | = | 6 | x | ( | 6 | x | ) |
| 30 | × | 30 | − | 30 | × | 3 | x | + | x | ( | 30 | − | 3 | x | ) | = | 6 | x | ( | 6 | x | ) |
| 30 | × | 30 | − | 30 | × | 3 | x | + | x | ( | 30 | − | 3 | x | ) | = | 6 | x | × | 6 | x |
| 900 | − | 90 | x | + | x | ( | 30 | − | 3 | x | ) | = | 36 | x | x |
| 900 | − | 90 | x | + | x | × | 30 | − | x | × | 3 | x | = | 36 | x | x |
| 900 | − | 60 | x | − | x | × | 3 | x | = | 36 | x | x |