A batch of coal was brought from the cafeteria, and the batch of coal was burned in 6 days (2/9), so how many days can the remaining coal be burned?
食堂运来一批煤，6天烧了这批煤的(2/9)，照这样，剩下的煤还能烧多少天？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 - (2/9)</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">(2/9) / 6</gadget>
<output>1/27 = around 0.037037</output>

<gadget id="calculator">(7/9) / (1/27)</gadget>
<output>21</output>

<result>21</result>