Students in the fifth and sixth grades of a certain school participated in plant labor. The sixth grade planted 80 trees, and the fifth grade planted 20% less than the sixth grade. How many trees were planted in the fifth grade?
某校五、六年级同学参加植物劳动，六年级植树80棵，五年级比六年级少植20%，五年级植树多少棵？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">80 * (4/5)</gadget>
<output>64</output>

<result>64</result>