A car travels 45 kilometers per hour and a truck travels 42 kilometers per hour. Cars and trucks leave opposite places A and B at the same time. If they met in 3 hours, how many kilometers are there between A and B?
一辆汽车每小时行45千米，一辆卡车每小时行42千米．汽车和卡车同时从甲、乙两地相对开出．3小时相遇，甲、乙两地相距多少千米？
<gadget id="calculator">45 + 42</gadget>
<output>87</output>

<gadget id="calculator">87 * 3</gadget>
<output>261</output>

<result>261</result>