A project can be completed by A alone in 10 days and B alone in 15 days. How many days can the two work together to complete the project (5/6).
一项工程，甲单独做10天完成，乙单独做15天完成．两人合作多少天可完成这项工程的(5/6)．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</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">(5/6) / (1/6)</gadget>
<output>5</output>

<result>5</result>