For a fraction, adding 2 to the denominator equals (2/5), and subtracting 3 from the denominator equals (1/2). What is this fraction?
一个分数，分母加上2后等于(2/5)，分母减去3后等于(1/2)，这个分数是多少？
<gadget id="calculator">25 - 2</gadget>
<output>23</output>

<gadget id="calculator">10 / 23</gadget>
<output>10/23 = around 0.434783</output>

<result>10/23 = around 0.434783</result>