One job can be done by A in 10 hours and by B in 15 hours. How many hours will it take (1/2) for A and B to do this job together?
一件工作，甲独做要10小时完成，乙独做要15小时完成．甲、乙合做这件工作的(1/2)需要用多少小时．
<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>