It takes 15 days for A to complete a job alone, and 10 days for B to complete it alone. If they work together at the same time, how many days can they complete half of the job?
一件工作，甲单独完成需要15天，乙单独完成需要10天，两同时合做，几天能完成这件工作的一半？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">(1/2) / (1/6)</gadget>
<output>3</output>

<result>3</result>