A box of colored pens, 12 are used up, and there is still (1/3), how many colored pens are there in this box?
一盒彩色笔，用去12支，还剩(1/3)，这盒彩色笔有多少支？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">12 / (2/3)</gadget>
<output>18</output>

<result>18</result>