Team A needs 6 days to complete a project, and team B needs 3 days to complete a project. If both teams A and B complete this project at the same time, how many days will it take in total?
A队做完一项工程需要6天，B队做完一项工程需要3天，如果A、B两队同时完成这项工程，一共需要多少天？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/6) + (1/3)</gadget>
<output>1/2 = around 0.5</output>

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

<result>2</result>