The sum of the numerator and denominator of a fraction is 38. If 3 is added to the numerator and denominator, the ratio of numerator to denominator is 4:7. What is the original fraction?
一个分数的分子、分母之和是38，如果把分子与分母各加上3，则分子与分母的比是4：7，原分数是多少．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(4/7) * 38</gadget>
<output>152/7 = around 21.714286</output>

<gadget id="calculator">(4/7) * 3</gadget>
<output>12/7 = around 1.714286</output>

<gadget id="calculator">(12/7) - 3</gadget>
<output>-9/7 = around -1.285714</output>

<gadget id="calculator">(152/7) + (-9/7)</gadget>
<output>143/7 = around 20.428571</output>

<gadget id="calculator">1 + (4/7)</gadget>
<output>11/7 = around 1.571429</output>

<gadget id="calculator">(143/7) / (11/7)</gadget>
<output>13</output>

<gadget id="calculator">38 - 13</gadget>
<output>25</output>

<gadget id="calculator">(143/7) / (11/7) / 25</gadget>
<output>13/25 = around 0.52</output>

<result>13/25 = around 0.52</result>