Cars A and B are traveling toward each other from A and B at the same time. After driving for 1.5 hours, the distance between the two cars is 87 kilometers; after driving for another 0.5 hours, the distance between the two cars is 38 kilometers. How many kilometers per hour?
甲乙两车同时从A、B两地相向而行，行驶1.5小时后两车相距87千米；又行驶了0.5小时后两车相距38千米，如果甲车每小时行42千米，乙车每小时行多少千米？
<gadget id="calculator">87 - 38</gadget>
<output>49</output>

<gadget id="calculator">49 / 0.5</gadget>
<output>98</output>

<gadget id="calculator">98 - 42</gadget>
<output>56</output>

<result>56</result>