Xiao Ming walks from home to a bookstore 720 meters away at a speed of 60 m/min. It takes him 10 minutes to get home. How much is the speed difference between when he got home and when he went there?
小明以60米/分的速度从家步行去720米以外的书店，回家的时候用了10分钟，回家时和去时的速度相差多少？
<gadget id="calculator">720 / 10</gadget>
<output>72</output>

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

<result>12</result>