A train travels from A to B. Because the speed of the train is increased, the arrival time is reduced from 36 hours to 30 hours. By what percentage is the speed of the train increased?
一列火车从甲地开往乙地，由于火车提速，到达的时间由原来的36小时减少到30小时，这列火车提速百分之几？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 36</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">(1/30) - (1/36)</gadget>
<output>1/180 = around 0.005556</output>

<gadget id="calculator">(1/180) / (1/36)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>