A project is done alone, A only needs 10 days, and B only needs 15 days. First, the two teams work together for a few days. After that, B leaves due to business, and A stays until the completion of the project. It takes 8 days from the start to the completion of the project. How many days have you been away?
一项工程，单独做，甲只要10天，乙只要15天，先由两队合做若干天后，乙队因事离开，甲留下直到完工，从开工到完成一共用了8天，乙队离开了几天？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 8</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/5) / (1/15)</gadget>
<output>3</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<result>5</result>