Adding 1 to the numerator of a fraction equals 1. If adding 1 to the denominator equals (4/5), what is the original fraction?
一个分数分子加1等于1，若分母加1等于(4/5)，原分数是多少
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<result>8/9 = around 0.888889</result>