| ( | 7 | ÷ | 31 | ) | × | 9 200 | + | ( | 24 | ÷ | 31 | ) | ( | 9 200 | a | + | 19 400 | ( | 1 | − | a | ) | ) | = | 93 2000 |
| 方程左边 = | 7 | ÷ | 31 | × | 9 200 | + | ( | 24 | ÷ | 31 | ) | ( | 9 200 | a | + | 19 400 | ( | 1 | − | a | ) | ) |
| = | 63 6200 | + | ( | 24 | ÷ | 31 | ) | ( | 9 200 | a | + | 19 400 | ( | 1 | − | a | ) | ) |
| = | 63 6200 | + | 24 | ÷ | 31 | × | ( | 9 200 | a | + | 19 400 | ( | 1 | − | a | ) | ) |
| = | 63 6200 | + | 24 31 | ( | 9 200 | a | + | 19 400 | ( | 1 | − | a | ) | ) |
| = | 63 6200 | + | 24 31 | × | 9 200 | a | + | 24 31 | × | 19 400 | ( | 1 | − | a | ) |
| = | 63 6200 | + | 27 775 | a | + | 57 1550 | ( | 1 | − | a | ) |
| = | 63 6200 | + | 27 775 | a | + | 57 1550 | × | 1 | − | 57 1550 | a |
| = | 63 6200 | + | 27 775 | a | + | 57 1550 | − | 57 1550 | a |
| = | 291 6200 | − | 3 1550 | a |
291 6200 | − | 3 1550 | a | = | 93 2000 |
| - | 3 1550 | a | = | 93 2000 | − | 291 6200 |
| - | 3 1550 | a | = | - | 27 62000 |
27 62000 | = | 3 1550 | a |
3 1550 | a | = | 27 62000 |
| a | = | 27 62000 | ÷ | 3 1550 |
| = | 27 62000 | × | 1550 3 |
| = | 9 40 | × | 1 |
| a | = | 9 40 |
| a | = | 0.225 |