The distance between A and B is 630 kilometers. Cars A and B drive from the two places at the same time and meet each other after 4.5 hours. It is known that car A travels 80 kilometers per hour. How many kilometers does car B travel per hour?
甲乙两地相距630千米，甲乙两车同时从两地相对开出，4.5小时后相遇，已知甲车每小时行80千米，乙车每小时行多少千米？
<gadget id="calculator">630 / 4.5</gadget>
<output>140</output>

<gadget id="calculator">140 - 80</gadget>
<output>60</output>

<result>60</result>