The distance between the two cities is 1440 kilometers. Two passenger cars A and B depart from the two cities at the same time and meet each other after 8 hours. It is known that car A travels 42 kilometers per hour, how many kilometers per hour does car B travel?
两城市相距1440千米，甲、乙两客车分别从两城市同时相对开出，经过8小时相遇．已知甲车每小时行驶42千米，求乙车每小时行驶多少千米？
<gadget id="calculator">1_440 / 8</gadget>
<output>180</output>

<gadget id="calculator">180 - 42</gadget>
<output>138</output>

<result>138</result>