| ( | ( | 216987 10 | + | a | + | 843 | + | 8000 | ) | − | 20000 | − | 843 | ) | × | 3 100 | = | 12509 100 | + | a |
| 方程左边 = | ( | 216987 10 | + | a | + | 843 | + | 8000 | ) | × | 3 100 | − | 20000 | × | 3 100 | − | 843 | × | 3 100 |
| = | ( | 216987 10 | + | a | + | 843 | + | 8000 | ) | × | 3 100 | − | 600 | − | 2529 100 |
| = | ( | 216987 10 | + | a | + | 843 | + | 8000 | ) | × | 3 100 | − | 62529 100 |
| = | 216987 10 | × | 3 100 | + | a | × | 3 100 | + | 843 | × | 3 100 | + | 8000 | × | 3 100 | − | 62529 100 |
| = | 650961 1000 | + | a | × | 3 100 | + | 2529 100 | + | 240 | − | 62529 100 |
| = | 290961 1000 | + | 3 100 | a |
290961 1000 | + | 3 100 | a | = | 12509 100 | + | a |
3 100 | a | − | a | = | 12509 100 | − | 290961 1000 |
| - | 97 100 | a | = | 12509 100 | − | 290961 1000 |
| - | 97 100 | a | = | - | 165871 1000 |
165871 1000 | = | 97 100 | a |
97 100 | a | = | 165871 1000 |
| a | = | 165871 1000 | ÷ | 97 100 |
| = | 165871 1000 | × | 100 97 |
| = | 165871 10 | × | 1 97 |
| a | = | 165871 970 |
| a | = | 171.001031 |