To produce a batch of toys, factory A takes 12 days to complete, and factory B takes 18 days to complete. After the two factories cooperate for 3 days, factory A will complete the rest alone. How many days will it take?
生产一批玩具，甲厂要12天完成，乙厂要18天完成，两厂合作3天后，剩下的由甲厂单独完成，还需要多少天？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/12) + (1/18)</gadget>
<output>5/36 = around 0.138889</output>

<gadget id="calculator">(5/36) * 3</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 - (5/12)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">(7/12) / (1/12)</gadget>
<output>7</output>

<result>7</result>