For a section of the road, car A takes 10 hours to travel alone, and car B takes 15 hours to travel alone. If two cars are traveling in the same direction, how many hours can they meet?
一段路，甲车单独行完要10小时，乙车单独行完要15小时．如果两车相向而行，几小时能相遇？
<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>