解下列方程.
| Χ+ | Χ-( | Χ+( |
| 500×2= | 400×5= | 7×30= | 28÷7= | 40÷5= |
| 53+7= | 28÷4= | 49+6= | 100-49= | 3600÷3= |
| 47-28= | 32÷8= | 230×7= | 55×4= | 789×0= |
| 500×8= | 1000×5= | 120×0= | 52÷7= | 300×9= |
| Χ+ | Χ-( | Χ+( |
| 500×2= | 400×5= | 7×30= | 28÷7= | 40÷5= |
| 53+7= | 28÷4= | 49+6= | 100-49= | 3600÷3= |
| 47-28= | 32÷8= | 230×7= | 55×4= | 789×0= |
| 500×8= | 1000×5= | 120×0= | 52÷7= | 300×9= |