The sum of the numerator and denominator of a simplest fraction is 40, and 3 is added to both the numerator and the denominator. After the reduction, it is (10/13). What is the simplest fraction?
一个最简分数的分子、分母的和是40，分子、分母都加上3，约分后是(10/13)，这个最简分数是多少？
<gadget id="calculator">10 / 13</gadget>
<output>10/13 = around 0.769231</output>

<gadget id="calculator">(10/13) * 40</gadget>
<output>400/13 = around 30.769231</output>

<gadget id="calculator">(10/13) * 3</gadget>
<output>30/13 = around 2.307692</output>

<gadget id="calculator">(30/13) - 3</gadget>
<output>-9/13 = around -0.692308</output>

<gadget id="calculator">(400/13) + (-9/13)</gadget>
<output>391/13 = around 30.076923</output>

<gadget id="calculator">1 + (10/13)</gadget>
<output>23/13 = around 1.769231</output>

<gadget id="calculator">(391/13) / (23/13)</gadget>
<output>17</output>

<gadget id="calculator">40 - 17</gadget>
<output>23</output>

<gadget id="calculator">(391/13) / (23/13) / 23</gadget>
<output>17/23 = around 0.73913</output>

<result>17/23 = around 0.73913</result>