It used to take 5 hours for a bus to travel from downtown Lianyungang to Nanjing, but now it only takes 4 hours. By what percentage is the time shortened? By what percentage did the bus speed up?
一辆客车从连云港市区到南京原来要5小时，现在只要4小时．时间缩短了百分之几？客车的速度加快了百分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) / (1/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>