Obviously going to the water park, if you go by car and walk back, it will take 30 minutes. If you take the car when you go and come back, it will take 10 minutes. Then, how many minutes will it take to walk back when you go.
明明去水上公园玩，如果去时坐车回来步行，需要30分钟，如果去时、回来都坐车，需要10分钟，那么，去时回来都步行需要多少分钟．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">30 - 5</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>