It is not a ratio because it should not be expressed as a mixed number
so you can express the mixed number like a fraction
[tex]\begin{gathered} 1\frac{13}{7} \\ \frac{(7\times1)+13}{7} \\ \frac{7+13}{7} \\ \\ =\frac{20}{7} \end{gathered}[/tex]20/7 is a ratio because is a fraction, the division between two numbers