Xiao Ming's distance from home to school is 540 meters, and it takes Xiao Ming 9 minutes to go to school, and it takes 3 minutes less to go home than to go to school. So how many meters per minute does Xiao Ming walk on average for a round trip?
小明从家到学校的路程是540米，小明上学要走9分钟，回家时比上学时少用3分钟．那么小明往返一趟平均每分钟走多少米？
<gadget id="calculator">540 * 2</gadget>
<output>1_080</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">9 + 6</gadget>
<output>15</output>

<gadget id="calculator">1_080 / 15</gadget>
<output>72</output>

<result>72</result>