simple true fraction whose product of numerator and denominator is 63, and the sum of numerator and denominator is 16, what is the fraction.
一个最简真分数，它的分子与分母的积是63，且分子与分母的和是16，这个分数是多少．
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

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