There is a simple fraction, the sum of its numerator and denominator is 30, after subtracting 3 from the numerator and denominator, the value of this fraction is (5/7) what is the original fraction.
有一个最简分数，它的分子与分母的和是30，分子和分母各减去3之后，这个分数的值是(5/7)原来分数是多少．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(5/7) * 30</gadget>
<output>150/7 = around 21.428571</output>

<gadget id="calculator">(5/7) * 3</gadget>
<output>15/7 = around 2.142857</output>

<gadget id="calculator">(150/7) - (15/7)</gadget>
<output>135/7 = around 19.285714</output>

<gadget id="calculator">3 + (135/7)</gadget>
<output>156/7 = around 22.285714</output>

<gadget id="calculator">1 + (5/7)</gadget>
<output>12/7 = around 1.714286</output>

<gadget id="calculator">(156/7) / (12/7)</gadget>
<output>13</output>

<gadget id="calculator">30 - 13</gadget>
<output>17</output>

<gadget id="calculator">(156/7) / (12/7) / 17</gadget>
<output>13/17 = around 0.764706</output>

<result>13/17 = around 0.764706</result>