A project A and B cooperate to complete in 10 days. If A works in 3 days and B works in 2 days, the project will be completed (4/15). Q: How many days will it take A to complete the project alone?
一件工程甲乙合作10天完成，如果甲做3天，乙做2天共完成这件工程的(4/15)．问：甲单独完成这项工程需多少天．
<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 2</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(4/15) - (1/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / (1/15)</gadget>
<output>15</output>

<result>15</result>