A bottle of cooking oil, Xiaohong has used it for 4 days and there is still left (2/3), how many days can this bottle of oil be used for?
一瓶食用油，小红家用了4天还剩(2/3)，这瓶油能用多少天．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 4</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>