Xiao Ming’s distance from home to school is 225 meters. Xiao Ming has to walk 5 minutes to go to school and 4 minutes to go home. So how many meters does Xiao Ming walk on average per minute for a round trip?
小明从家到学校的路程是225米，小明上学要走5分钟，回家时走四分钟，那么小明往返一趟平均每分钟走多少米？
<gadget id="calculator">225 * 2</gadget>
<output>450</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">450 / 9</gadget>
<output>50</output>

<result>50</result>