car travels 20 meters per second. When it just entered the tunnel, it found a passenger car driving 180 meters ahead. If the speed of the two cars remains the same, and the two cars drive out of the tunnel at the same time after 1.5 minutes, how many meters per second will the passenger car travel?
一辆小汽车每秒行20米，刚驶入隧道时，发现一辆客车正在前面180米处行驶．如果两车速度保持不变，1.5分钟后两车同时驶出隧道，那么客车每秒行驶多少米．
<gadget id="calculator">20 * 90</gadget>
<output>1_800</output>

<gadget id="calculator">1_800 - 180</gadget>
<output>1_620</output>

<gadget id="calculator">1_620 / 90</gadget>
<output>18</output>

<result>18</result>