To add these fractions, we can do the following steps.
Step 1: Simplify each fraction.
[tex]\frac{25}{5y}=\frac{5\cdot5}{5y}=\frac{5}{y}[/tex][tex]\frac{64}{8y}=\frac{8\cdot8}{8y}=\frac{8}{y}[/tex]Step 2: We add the numerators since the fractions have the same denominator.
[tex]\frac{5}{y}+\frac{8}{y}=\frac{5+8}{y}=\frac{13}{y}[/tex]Therefore, the result of adding the fractions is 13/y.