The sum of the numerator and the denominator of a fraction is 80, which is (7/9) after division. What is the fraction.
一个分数的分子、分母之和是80，约分后是(7/9)，这个分数是多少．
<gadget id="calculator">7 + 9</gadget>
<output>16</output>

<gadget id="calculator">7 / 16</gadget>
<output>7/16 = around 0.4375</output>

<gadget id="calculator">9 / 16</gadget>
<output>9/16 = around 0.5625</output>

<gadget id="calculator">80 * (9/16)</gadget>
<output>45</output>

<gadget id="calculator">(7/16) / 45</gadget>
<output>7/720 = around 0.009722</output>

<gadget id="calculator">80 * (7/720)</gadget>
<output>7/9 = around 0.777778</output>

<result>7/9 = around 0.777778</result>