| 417 | = | 80 | a | × | 1 | ÷ | ( | 80 | + | 198 | ) |
| 方程两边同时乘以: | ( | 80 | + | 198 | ) |
| 417 | ( | 80 | + | 198 | ) | = | 80 | a | × | 1 |
| 417 | × | 80 | + | 417 | × | 198 | = | 80 | a | × | 1 |
| 33360 | + | 82566 | = | 80 | a |
| 115926 | = | 80 | a |
| - | 80 | a | = | - | 115926 |
| 115926 | = | 80 | a |
| 80 | a | = | 115926 |
| a | = | 115926 | ÷ | 80 |
| = | 115926 | × | 1 80 |
| = | 57963 | × | 1 40 |
| a | = | 57963 40 |
| a | = | 1449.075 |