Dongdong has 300 meters from home to school, and he walks 60 meters per minute on average, how many minutes does it take to go back and forth.
冬冬从家到学校有300米，他平均每分钟行60米，往返一次需要多少分钟．
<gadget id="calculator">300 / 60</gadget>
<output>5</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>