Cars A and B travel toward each other for 3.6 hours with a distance of 306 kilometers. Car A travels 42 kilometers per hour. How many kilometers does Car B travel per hour?
甲乙两车相背而行3.6小时相距306千米，甲车每小时行42千米，乙车每小时行多少千米？
<gadget id="calculator">306 / 3.6</gadget>
<output>85</output>

<gadget id="calculator">85 - 42</gadget>
<output>43</output>

<result>43</result>