A train of passenger cars and a train of freight trains travel at the same time and at the same place in opposite directions, and the distance between them is 400 km after 4 hours. It is known that the passenger car travels 48 kilometers per hour, how many kilometers per hour does the truck travel?
一列客车和一列货车同时、同地反向而行，4小时后相距400千米．已知客车每小时行48千米，货车每小时行多少千米？
<gadget id="calculator">400 / 4</gadget>
<output>100</output>

<gadget id="calculator">100 - 48</gadget>
<output>52</output>

<result>52</result>