解:7×9+12÷(3-2)=75 (7×9+12)÷3-2=23
1.(7×9+12)÷3-2=23 2. 7×(9+12)÷3-2=47 3.(7×9+12)÷(3-2)=75 4. 7×((9+12)÷3-2)=35
7×9+12÷(3-2)=75(7×9+12)÷3-2=23
(7×9+12)÷(3-2)=75 (7×9+12)÷3-2=23
第四道、 7×[(9+12)÷3-2]=35