For a fraction, the sum of the numerator and the denominator is 28. If 2 is added to the numerator and 2 is subtracted from the denominator, the fraction obtained after division is (1/3). Find the original fraction.
一个分数，分子与分母的和是28，如果分子加上2，分母减去2，所得分数约分后是(1/3)，求原分数．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">28 - 5</gadget>
<output>23</output>

<gadget id="calculator">5 / 23</gadget>
<output>5/23 = around 0.217391</output>

<result>5/23 = around 0.217391</result>