Add 7 to the numerator of a fraction, subtract 7 from the denominator, and the new fraction obtained is (3/4), what is the original fraction.
一个分数的分子加上7，分母减去7，得到的新分数约分后是(3/4)，这个分数原来是多少．
<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<gadget id="calculator">12 + 7</gadget>
<output>19</output>

<gadget id="calculator">2 / 19</gadget>
<output>2/19 = around 0.105263</output>

<result>2/19 = around 0.105263</result>