The distance between A and B is 520 kilometers. A passenger car and a freight train leave from the two places at the same time. After 4 hours of meeting, it is known that the passenger car travels 75 kilometers per hour. How many kilometers per hour does the truck travel?
甲乙两地相距520千米，一列客车和一列货车同时从两地相对开出，经过4小时相遇，已知客车每小时行75千米，货车每小时行多少千米？
<gadget id="calculator">520 / 4</gadget>
<output>130</output>

<gadget id="calculator">130 - 75</gadget>
<output>55</output>

<result>55</result>