The highway from Huzhou to Shanghai has a total length of 168 kilometers. Two cars, A and B, drive from the two cities at the same time. After 4 hours of intersection, the speed of car A is twice that of car B. How many kilometers does car B travel per hour?
湖州到上海的公路全长168千米，甲乙两辆汽车分别从两城同时相对开出，经过4小时交汇，甲车的速度是乙车的2倍．乙车每小时行驶多少千米？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">168 / 4 / 3</gadget>
<output>14</output>

<result>14</result>