For a fraction ((b)/(a)), subtract 2 from its denominator, that is ((b)/(a-2)), which equals (3/4) after reduction; if the denominator of the original fraction is added 9, that is ((b)/(a+9)), equal to (5/7) after reduction, then ((b)/(a)) = how much.
一个分数((b)/(a))，把它的分母减2，即((b)/(a-2))，约分后等于(3/4)；如果原来的分数的分母加上9，即((b)/(a+9))，约分后等于(5/7)，则((b)/(a))=多少．
<gadget id="calculator">220 + 2</gadget>
<output>222</output>

<gadget id="calculator">165 / 222</gadget>
<output>55/74 = around 0.743243</output>

<result>55/74 = around 0.743243</result>