There used to be 6 classes in the fourth grade of Experimental Primary School, with an average of 80 students in each class. After moving to the new teaching building, the average number of students in each class was reduced by 20. How many classes are there in the fourth grade of Experimental Primary School?
实验小学四年级原来有6个班，平均每班80人，搬到新教学楼后，平均每班人数减少20人，实验小学四年级现在有几个班？
<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<gadget id="calculator">6 / 60</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">80 * (1/10)</gadget>
<output>8</output>

<result>8</result>