A project can be completed by team A alone in 18 days; team B alone can complete the entire project in 15 days (2/3). How many days can the project be completed if the two teams work together?
一项工程，甲队单独做需要18天完成；乙队单独做15天完成全部工程的(2/3)．如果两队合做，多少天可完成这项工程？
<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

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

<gadget id="calculator">(2/3) / 15</gadget>
<output>2/45 = around 0.044444</output>

<gadget id="calculator">(1/18) + (2/45)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / (1/10)</gadget>
<output>10</output>

<result>10</result>