The distance between A and B is 480 kilometers. The bus and the truck meet each other after 4 hours. The bus travels 70 kilometers per hour. How many kilometers per hour does the truck travel?
甲乙两地相距480千米，客车和货车相对开出经过4小时相遇，客车每小时行70千米，货车每小时行多少千米？
<gadget id="calculator">480 / 4</gadget>
<output>120</output>

<gadget id="calculator">120 - 70</gadget>
<output>50</output>

<result>50</result>