| 30000 | ÷ | a | + | 10000 | ÷ | ( | a | + | 60 | ) | = | 150 |
| 方程两边同时乘以: | a |
| 30000 | + | 10000 | ÷ | ( | a | + | 60 | ) | × | a | = | 150 | a |
| 方程两边同时乘以: | ( | a | + | 60 | ) |
| 30000 | ( | a | + | 60 | ) | + | 10000 | a | = | 150 | a | ( | a | + | 60 | ) |
| 30000 | a | + | 30000 | × | 60 | + | 10000 | a | = | 150 | a | ( | a | + | 60 | ) |
| 30000 | a | + | 30000 | × | 60 | + | 10000 | a | = | 150 | a | a | + | 150 | a | × | 60 |
| 30000 | a | + | 1800000 | + | 10000 | a | = | 150 | a | a | + | 9000 | a |
| 40000 | a | + | 1800000 | = | 150 | a | a | + | 9000 | a |