The railway from City A to City B is 468 kilometers long. It used to take 5.2 hours for express trains to travel, but now it only takes 3.9 hours. How much more kilometers per hour is the average travel now than in the past?
从甲城到乙城铁路长468千米，以前快车要行5.2小时，现在只要行3.9小时，现在比过去平均每小时多行多少千米？
<gadget id="calculator">468 / 3.9</gadget>
<output>120</output>

<gadget id="calculator">468 / 5.2</gadget>
<output>90</output>

<gadget id="calculator">120 - 90</gadget>
<output>30</output>

<result>30</result>