A car departs from Xiamen to Fuzhou, travels for 3 hours, travels 100 kilometers per hour, and travels for 4 hours when it returns to Xiamen, how many kilometers per hour does the car travel when it returns?
一辆汽车从厦门出发到福州，行了3小时，每小时行100千米，返回厦门时汽车行了4小时，汽车返回时每小时行多少千米？
<gadget id="calculator">100 * 3</gadget>
<output>300</output>

<gadget id="calculator">300 / 4</gadget>
<output>75</output>

<result>75</result>