The highway from Chongqing to Guiyang is 500 kilometers long. At 8:00 in the morning, a passenger car drove from Guiyang to Chongqing, and at the same time, a truck drove from Chongqing to Guiyang, and they met at 12:00 noon. The passenger car travels 80 kilometers per hour, how many kilometers per hour does the truck travel?
重庆至贵阳的高速路长500千米．早上8：00一辆客车从贵阳开往重庆，同时一辆货车从重庆开往贵阳，中午12：00它们相遇．客车每时行80千米，货车每小时行多少千米？
<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">500 / 4</gadget>
<output>125</output>

<gadget id="calculator">125 - 80</gadget>
<output>45</output>

<result>45</result>