Students in 6 classes of the fifth grade carried out specimen collection activities, with an average of 20 specimens collected per class. Put these specimens on 4 racks, how many specimens are placed on each rack?
五年级6个班的同学开展采集标本活动，平均每班采集20个标本．把这些标本放在4个架子上，平均每个架子放多少个标本？
<gadget id="calculator">6 / 4</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">20 * (3/2)</gadget>
<output>30</output>

<result>30</result>