Obviously bought 12 colored pens, 4 of which are red, and red accounts for ((())/(())) of the total number of colored pens.
明明买来12支彩笔，其中有4支是红色的，红色占彩笔总数的((())/(()))．
<gadget id="calculator">4 / 12</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>