4 | ÷ | 3 | × | a | × | 20 | + | 100 | ( | 300 | − | 7 | a | ) | ÷ | 9 | = | 2260 |
方程左边 = | 80 3 | a | + | 100 9 | ( | 300 | − | 7 | a | ) |
80 3 | a | + | 100 9 | ( | 300 | − | 7 | a | ) | = | 2260 |
方程左边 = | 80 3 | a | + | 100 9 | × | 300 | − | 100 9 | × | 7 | a |
= | 80 3 | a | + | 10000 3 | − | 700 9 | a |
= | - | 460 9 | a | + | 10000 3 |
- | 460 9 | a | + | 10000 3 | = | 2260 |
- | 460 9 | a | = | 2260 | − | 10000 3 |
- | 460 9 | a | = | - | 3220 3 |
3220 3 | = | 460 9 | a |
460 9 | a | = | 3220 3 |
a | = | 3220 3 | ÷ | 460 9 |
= | 3220 3 | × | 9 460 |
= | 7 | × | 3 |
a | = | 21 |