The passenger car travels 100 kilometers per hour, and the speed of the truck is slower than the passenger car (1/5), how many kilometers per hour does the truck travel?
客车每小时行100千米，货车比客车的速度慢(1/5)，货车每小时行多少千米？
<gadget id="calculator">1 / 5</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">100 * (4/5)</gadget>
<output>80</output>

<result>80</result>