The school bought 300 floppy disks and bought 20% less CDs than floppy disks. How many CDs did they buy?
学校买来300张软盘，买来的光盘比软盘少20%，买来光盘多少张？
<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">300 * (4/5)</gadget>
<output>240</output>

<result>240</result>