Li Shuang rode his bicycle from point A to point B at a speed of 320 meters per minute. On the way, due to a bicycle breakdown, he pushed the cart and continued to walk for 5 minutes to a place 1,800 meters away from point B for repair. After 15 minutes, he continued to ride at the original speed. 1.5 times of 1.5 times and continue to move forward to point B. When arriving at point B, it takes 17 minutes longer than the expected time. What is the walking speed of Li Shuang's cart in meters per minute?
李双骑车以320米分钟的速度从A地驶向B地，途中因自行车故障推车继续向前步行5分钟到距B地1800米的某地修车，15分钟后以原来骑车速度的1.5倍继续向前驶向B地，到达B地时，比预计时间多用17分钟，则李双推车步行的速度是多少米/分钟．
<gadget id="calculator">17 - 15</gadget>
<output>2</output>

<gadget id="calculator">1_800 / 320</gadget>
<output>45/8 = around 5.625</output>

<gadget id="calculator">320 * 1.5</gadget>
<output>480</output>

<gadget id="calculator">1_800 / 480</gadget>
<output>15/4 = around 3.75</output>

<gadget id="calculator">(45/8) - (15/4)</gadget>
<output>15/8 = around 1.875</output>

<gadget id="calculator">2 + (15/8)</gadget>
<output>31/8 = around 3.875</output>

<gadget id="calculator">5 - (31/8)</gadget>
<output>9/8 = around 1.125</output>

<gadget id="calculator">(9/8) / 5</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">320 * (9/40)</gadget>
<output>72</output>

<result>72</result>