Students go on an autumn outing. The car travels at a speed of 30 kilometers per hour for 2 hours, and there are still 12 kilometers to the end of the journey. If it takes 2 hours to return to school, how many kilometers per hour must the car travel?
同学们去秋游，汽车以每小时30千米的速度行驶2小时，距全程终点还有12千米，如果要求返回学校用2个小时，那么汽车每小时必须行多少千米？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">60 + 12</gadget>
<output>72</output>

<gadget id="calculator">72 / 2</gadget>
<output>36</output>

<result>36</result>