The school library purchased 80 science and technology books, 20% less than the purchase of story books. How many story books does the school library purchase?
学校图书馆购进科技书80本，比购进的故事书少20%．学校图书馆购进故事书多少本？
<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>100</output>

<result>100</result>