Build a road. Team A completed it in 10 weeks alone, and Team B completed it in 15 weeks alone. Two teams repair from both ends of the road at the same time, how many weeks can it be completed?
修一条公路．甲队单独修10周完成，乙队单独修15周完成．两队同时从公路两端修，几周可以完成？
<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>