It takes 40 seconds for a train to pass through a 530-meter cave, and 30 seconds to pass through a 380-meter cave. Ask: How many meters does the train travel per minute?
一辆火车穿过530米的山洞要40秒，穿过380米的山洞要30秒，问：火车每分钟行多少米．
<gadget id="calculator">530 - 380</gadget>
<output>150</output>

<gadget id="calculator">40 - 30</gadget>
<output>10</output>

<gadget id="calculator">150 / 10</gadget>
<output>15</output>

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

<result>900</result>