| 30000000 | = | x | × | 3 50 | ÷ | ( | 9 10000000000 | ( | 1 | + | x | ) | ÷ | x | ) |
| 方程两边同时乘以: | ( | 9 10000000000 | ( | 1 | + | x | ) | ÷ | x | ) |
| 30000000 | ( | 9 10000000000 | ( | 1 | + | x | ) | ÷ | x | ) | = | x | × | 3 50 |
| 30000000 | × | 9 10000000000 | ( | 1 | + | x | ) | ÷ | x | = | x | × | 3 50 |
27 1000 | ( | 1 | + | x | ) | ÷ | x | = | x | × | 3 50 |
| 方程两边同时乘以: | x |
27 1000 | ( | 1 | + | x | ) | = | 3 50 | x | x |
27 1000 | × | 1 | + | 27 1000 | x | = | 3 50 | x | x |
27 1000 | + | 27 1000 | x | = | 3 50 | x | x |