For a simplest fraction, add 1 to the numerator to get (1/2), and subtract 1 to get (4/9), what is the original fraction?
一个最简分数，分子加1可得到(1/2)，分子减去1可得(4/9)，原分数是多少．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 + 9</gadget>
<output>17</output>

<gadget id="calculator">9 - 8</gadget>
<output>1</output>

<gadget id="calculator">17 / 1</gadget>
<output>17</output>

<gadget id="calculator">17 + 1</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">17 / 1 / 36</gadget>
<output>17/36 = around 0.472222</output>

<result>17/36 = around 0.472222</result>