| ( | 4580 | − | ( | 100 | y | × | 13 100 | − | 500 | ) | × | 12 100 | ) | ÷ | y | = | 100 |
| 方程两边同时乘以: | y |
| ( | 4580 | − | ( | 100 | y | × | 13 100 | − | 500 | ) | × | 12 100 | ) | = | 100 | y |
| 4580 | − | ( | 100 | y | × | 13 100 | − | 500 | ) | × | 12 100 | = | 100 | y |
| 4580 | − | 100 | y | × | 13 100 | × | 12 100 | + | 500 | × | 12 100 | = | 100 | y |
| 4580 | − | 39 25 | y | + | 60 | = | 100 | y |
| 4640 | − | 39 25 | y | = | 100 | y |
| - | 39 25 | y | − | 100 | y | = | - | 4640 |
| - | 2539 25 | y | = | - | 4640 |
| 4640 | = | 2539 25 | y |
2539 25 | y | = | 4640 |
| y | = | 4640 | ÷ | 2539 25 |
| = | 4640 | × | 25 2539 |
| y | = | 116000 2539 |
| y | = | 45.687278 |