Wang Qiang walks 50 meters per minute from home to school, and arrives at school in 18 minutes; when he returns home from school, he wants to get home in 3 minutes less than when he went to school. How many meters should he walk per minute? (Solve with ratio)
王强从家到学校每分钟走50米，18分钟到校；放学回家时，他想比上学时少用3分钟到家，他每分钟应走多少米？(用比例解)
<gadget id="calculator">50 * 18</gadget>
<output>900</output>

<gadget id="calculator">18 - 3</gadget>
<output>15</output>

<gadget id="calculator">900 / 15</gadget>
<output>60</output>

<result>60</result>