It takes 4 days for A to complete (1/3) of a project, and 8 days for B to complete (2/5) of this project.
甲完成一项工程的(1/3)要4天，乙完成这项工程的(2/5)要8天，甲、乙合作每天完成这项工程的几分之几？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 / (1/3)</gadget>
<output>12</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">8 / (2/5)</gadget>
<output>20</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/12) + (1/20)</gadget>
<output>2/15 = around 0.133333</output>

<result>2/15 = around 0.133333</result>