Two cars A and B are driving from the same place in opposite directions at the same time. After 4 hours, the distance between the two cars is 300 kilometers. It is known that car A travels 40 kilometers per hour, how many kilometers per hour does car B travel?
甲乙两辆汽车同时从同一地点向相反的方向行驶，4小时后两车相距300千米，已知甲车每小时行40千米，乙车每小时行多少千米？
<gadget id="calculator">300 / 4</gadget>
<output>75</output>

<gadget id="calculator">75 - 40</gadget>
<output>35</output>

<result>35</result>