There are two biggest differences between Arctic reindeer and other deer species in the world: one is that female deer have branch-like horns like stags, and the other is that reindeer migrate south in winter like migratory birds, and start to march north in early spring ． Often travel long distances of 500-700 kilometers, or even thousands of kilometers. Some people also domesticate reindeer and pull sleds, but its speed is not as fast as that of penguins. Penguins can ski at a speed of up to 30 kilometers per hour, which is 4 kilometers less than twice that of reindeer. What is the speed of the reindeer pulling the sled?
北极驯鹿与世界其他鹿种最大的不同有两点：一是雌鹿同雄鹿一样都长着树枝般的角，二是驯鹿像候鸟一样人冬时节往南迁移，早春时节，开始向北进发．常常长途跋涉500～700千米，甚至上千千米．人们也有的把驯鹿驯养后拉雪橇，但它的速度比不上企鹅的速度．企鹅滑雪时速最高可达30千米，比驯鹿的2倍少4千米．驯鹿拉雪橇的时速是多少千米？
<gadget id="calculator">30 + 4</gadget>
<output>34</output>

<gadget id="calculator">34 / 2</gadget>
<output>17</output>

<result>17</result>