The distance between A and B is 400 kilometers. The passenger car and the truck leave from the two places at the same time and drive towards each other. They meet each other in 4 hours. It is known that the truck travels 53 kilometers per hour. How many kilometers does the passenger car travel per hour?
甲乙两地相距400千米，客车和货车同时从两地相对开出，相向而行，4小时相遇，已知货车每小时行53千米，问客车每小时行多少千米？
<gadget id="calculator">400 / 4</gadget>
<output>100</output>

<gadget id="calculator">100 - 53</gadget>
<output>47</output>

<result>47</result>