Yimin Primary School planted 180 trees. Among them, (1/5) was planted in the sixth grade, and (1/4) was planted in the fifth grade. How many trees were planted in the sixth grade?
益民小学植树180棵．其中(1/5)是六年级种的，(1/4)是五年级种的，六年级一共植了多少棵树？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">180 * (1/5)</gadget>
<output>36</output>

<result>36</result>