The distance between A and B is 420 kilometers. A car travels from A to B in 7 hours, but actually travels 70 kilometers per hour. How many hours did you arrive earlier than planned?
甲乙两地相距420千米，一辆汽车从甲地到乙地计划用7小时到达，实际每小时行了70千米．实际比计划提前了几小时到达？
<gadget id="calculator">420 / 70</gadget>
<output>6</output>

<gadget id="calculator">7 - 6</gadget>
<output>1</output>

<result>1</result>