It takes A 10 hours to do a job alone, and B 15 hours to do it alone. If Team B does it alone for 5 hours first, and then the two teams work together to do the rest, how many hours will it take?
一件工作，甲单独做要用10小时，乙单独做要用15小时，如果先由乙队单独做5小时后，余下的工作两队合做，还要几小时？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 5</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

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

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

<gadget id="calculator">(2/3) / (1/6)</gadget>
<output>4</output>

<result>4</result>