A highway connects cities A and B. It takes 10 hours for a car to travel from city A to city B, and 15 hours for a truck to travel from city B to city A. Two cars depart from opposite sides of the two cities at the same time, how many hours will they meet?
一条高速公路连接甲乙两城，小轿车从甲城到达乙城要10小时，卡车从乙城到达甲城要15小时．两车同时从两城相对开出，几小时相遇？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<result>6</result>