A project is completed by Team A in 15 days alone, and the ratio of work efficiency between Team B and Team A is 3:2. How many days will it take for the two teams to work together?
一件工程，甲队独作15天完成，乙队与甲队的工作效率之比是3：2．两队合作，多少天能完成．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(1/15) / (2/3)</gadget>
<output>1/10 = around 0.1</output>

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

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

<result>6</result>