The numerator and denominator of a fraction are divided by the same number at the same time (7/9). The original sum of the numerator and denominator is 80. What is the original fraction?
一个分数的分子和分母同时除以一个相同的数是(7/9)，原来分子与分母的和是80，这个分数原来是多少？
<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>