Fraction $\frac{-3}{5}$ can be rewritten as $-\frac{3}{5}$ by extracting the negative sign.
$$sort(-\frac{3}{5},\frac{7}{9})$$
Least common denominator of the numbers in the list $-\frac{3}{5},\frac{7}{9}$ is $45$. Convert numbers in the list to fractions with denominator $45$.
