Yinchuan Department Store originally had 500 TV sets, but 20% of them were purchased last month, and 20% were shipped in later. How many sets are there at this time?
银川百货大楼原有500台电视机，上个月买掉了20%，后来又运进了20%，这时有多少台．
<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">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">500 * (4/5) * (6/5)</gadget>
<output>480</output>

<result>480</result>