For a fraction, 2 is added to the numerator to get (3/5), and 2 is subtracted from the numerator to get (1/3). What is the fraction?
一个分数，分子加上2得(3/5)，分子减去2得(1/3)，这个分数是多少．
<gadget id="calculator">9 - 2</gadget>
<output>7</output>

<gadget id="calculator">7 / 15</gadget>
<output>7/15 = around 0.466667</output>

<result>7/15 = around 0.466667</result>