The total length of the railway from City A to City B is 630 kilometers, and a train travels 280 kilometers in 4 hours. According to this calculation, how many hours does it take to travel from City A to City B? (Solution by ratio)
从甲城到乙城铁路全长630千米，一列火车4小时行驶280千米，照这样计算，从甲城到乙城需要几小时？(用比列解)
<gadget id="calculator">280 / 4</gadget>
<output>70</output>

<gadget id="calculator">630 / 70</gadget>
<output>9</output>

<result>9</result>