The road between A and B is 420 kilometers long. It takes 3 hours for a car to travel from A to B, and it takes 3/7 of the journey. How many kilometers does the car travel per hour?
甲、乙两地之间公路长420千米，一辆汽车从甲地开往乙地，用了3小时，行了全程的(3/7)，这辆汽车每小时行多少千米？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) / 3</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">420 * (1/7)</gadget>
<output>60</output>

<result>60</result>