There is a fraction that is reduced to the simplest fraction (7/13). The sum of the numerator and denominator before the reduction is 200. What is the fraction before the reduction?
有一个分数约成最简分数后是(7/13)，约分前分子与分母的和是200，约分前的分数是多少？
<gadget id="calculator">7 + 13</gadget>
<output>20</output>

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">13 / 20</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">200 * (13/20)</gadget>
<output>130</output>

<gadget id="calculator">(7/20) / 130</gadget>
<output>7/2_600 = around 0.002692</output>

<gadget id="calculator">200 * (7/2_600)</gadget>
<output>7/13 = around 0.538462</output>

<result>7/13 = around 0.538462</result>