8000 | + | 7200 | + | x | = | 3 | ( | x | − | 400 | ) |
方程左边 = | 15200 | + | x |
15200 | + | x | = | 3 | ( | x | − | 400 | ) |
方程右边 = | 3 | x | − | 3 | × | 400 |
= | 3 | x | − | 1200 |
15200 | + | x | = | 3 | x | − | 1200 |
x | − | 3 | x | = | - | 1200 | − | 15200 |
- | 2 | x | = | - | 1200 | − | 15200 |
- | 2 | x | = | - | 16400 |
16400 | = | 2 | x |
2 | x | = | 16400 |
x | = | 16400 | ÷ | 2 |
= | 16400 | × | 1 2 |
= | 8200 | × | 1 |
x | = | 8200 |