Li Ming sent a truckload of goods to the supermarket at a speed of 45 kilometers per hour. It took 2 hours to deliver it, and it only took 1 hour and 30 minutes to return. How many kilometers per minute did he travel on average when he returned?
李明把一车货物送到超市，去时的速度为45千米/时，用了2小时送到，返回时只用了1小时30分，返回时平均每分钟行驶多少千米？
<gadget id="calculator">2 / 90</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">45 * (1/45)</gadget>
<output>1</output>

<result>1</result>