A truck and a passenger car leave from two places 320 kilometers apart at the same time, the truck travels 40 kilometers per hour, and the passenger car takes 4 hours less than the truck to complete the journey. How many kilometers does the bus travel per hour?
一辆货车和一辆客车同时从相距320千米的两地相对开出，货车每时行驶40千米，行驶完全程客车比货车少用4时．客车每时行驶多少千米？
<gadget id="calculator">320 / 40</gadget>
<output>8</output>

<gadget id="calculator">8 - 4</gadget>
<output>4</output>

<gadget id="calculator">320 / 4</gadget>
<output>80</output>

<result>80</result>