There is a fraction, add 7 to its denominator, after simplification (4/15), subtract 7 from the denominator, it can be reduced to (1/2), what is this fraction?
有一个分数，它的分母加7，化简后(4/15)，分母减7，可约分为(1/2)，这个分数是多少？
<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">23 + 7</gadget>
<output>30</output>

<gadget id="calculator">(4/15) * 30</gadget>
<output>8</output>

<gadget id="calculator">8 / 23</gadget>
<output>8/23 = around 0.347826</output>

<result>8/23 = around 0.347826</result>