A project can be completed by team A alone in 15 hours, and team B can be completed in 10 hours alone, how many hours can the two teams work together to complete half of the project.
一项工程甲队单独做15小时可以完成，乙队单独做10小时可以完成，两队合多少小时可以完成这项工程的一半．
<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>