A project is completed in 10 days jointly by A and B. The ratio of work efficiency between A and B is 2:3, how many days will it take for A to complete this project alone?
一项工程，甲、乙合做10天完成．甲、乙工作效率的比是2：3，求甲单独完成这项工程需要多少天？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

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

<gadget id="calculator">10 / (2/5)</gadget>
<output>25</output>

<result>25</result>