A project can be completed by A alone in 15 days, and B can complete (1/10) of the project every day. How many days can the two teams work together to complete the entire project?
一项工程，甲独做15天完成，乙每天完成工程的(1/10)，现两队合做多少天可完成全部工程．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 10</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>