| 10000 | + | 125 | y | + | 90 100 | × | 125 | ( | 66 | − | y | ) | = | 27600 |
| 方程左边 = | 10000 | + | 125 | y | + | 225 2 | ( | 66 | − | y | ) |
| 10000 | + | 125 | y | + | 225 2 | ( | 66 | − | y | ) | = | 27600 |
| 方程左边 = | 10000 | + | 125 | y | + | 225 2 | × | 66 | − | 225 2 | y |
| = | 10000 | + | 125 | y | + | 7425 | − | 225 2 | y |
| = | 17425 | + | 25 2 | y |
| 17425 | + | 25 2 | y | = | 27600 |
25 2 | y | = | 27600 | − | 17425 |
25 2 | y | = | 10175 |
| y | = | 10175 | ÷ | 25 2 |
| = | 10175 | × | 2 25 |
| = | 407 | × | 2 |
| y | = | 814 |