The distance between A and B is 720 kilometers. It takes 9 hours for a car to drive from A to B. If the car is required to arrive at B 1 hour earlier. How much km/h should the average speed of the car be increased?
甲、乙两地相距720千米，一辆汽车从甲地开往乙地需要9小时，如果要求汽车提前1小时到达乙地．汽车平均速度应提高多少千米/时？
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">720 / 8</gadget>
<output>90</output>

<gadget id="calculator">720 / 9</gadget>
<output>80</output>

<gadget id="calculator">90 - 80</gadget>
<output>10</output>

<result>10</result>