A certain project can be completed by A alone in 10 days, and B can complete it by doing 15 more. A and B can complete it in 12 days, A can do it in 8 days, and then B can do it alone. How many days will it take to complete?
某工程甲单独做10天，乙再做15可以完成，甲乙两人12天完成，甲做8天，然后乙再单独做，还要几天才能完成？
<gadget id="calculator">10 - 8</gadget>
<output>2</output>

<gadget id="calculator">15 / 10</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">2 * (3/2)</gadget>
<output>3</output>

<gadget id="calculator">15 + 3</gadget>
<output>18</output>

<result>18</result>