In the activity of collecting tree species for greening the motherland, there are 6 classes in the fourth grade of a certain school, and each class collects 20 kg of tree species; 3 classes in the fifth grade collect 60 kg in total. How many kilograms of tree species are collected by each class in the fourth and fifth grades?
在绿化祖国采集树种的活动中，某校四年级有6个班级，每班采集树种20千克；五年级3个班共采集60千克．四、五年级平均每班采集树种多少千克？
<gadget id="calculator">20 * 6</gadget>
<output>120</output>

<gadget id="calculator">120 + 60</gadget>
<output>180</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">180 / 9</gadget>
<output>20</output>

<result>20</result>