For a fraction in its simplest form, the value of the fraction after adding 1 to the numerator is equal to 1, and the value of the fraction after adding 1 to the denominator is equal to (2/3). What is the original fraction?
一个最简分数，分子加1后分数值等于1，分母加1后分数值等于(2/3)，原来的分数是多少？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">4 / 1 / 5</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>