Guanghua Elementary School uses a computer to type a document. It takes Xiao Li 10 hours to type it alone, and Xiao Zhang 15 hours to type it alone. Now Xiao Li and Xiao Zhang type it together. How many hours will it take to complete half of the manuscript?
光华小学用电脑打一份文件，小李单独打要10小时，小张单独打要15小时，现在小李、小张合打，几小时完成这份稿件的一半？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<result>3</result>