| ( | 100 | + | ( | a | − | 1 | ) | × | 258 | ) | ÷ | 16 | = | a | × | 258 | ÷ | 25 |
| 方程左边 = | 100 | × | 1 16 | + | ( | a | − | 1 | ) | × | 258 | × | 1 16 |
| = | 25 4 | + | ( | a | − | 1 | ) | × | 129 8 |
| = | 25 4 | + | a | × | 129 8 | − | 1 | × | 129 8 |
| = | 25 4 | + | a | × | 129 8 | − | 129 8 |
| = | - | 79 8 | + | 129 8 | a |
| - | 79 8 | + | 129 8 | a | = | a | × | 258 | ÷ | 25 |
| 方程右边 = | a | × | 258 25 |
| - | 79 8 | + | 129 8 | a | = | 258 25 | a |
129 8 | a | − | 258 25 | a | = | 79 8 |
1161 200 | a | = | 79 8 |
| a | = | 79 8 | ÷ | 1161 200 |
| = | 79 8 | × | 200 1161 |
| = | 79 | × | 25 1161 |
| a | = | 1975 1161 |
| a | = | 1.70112 |