Respuesta :

[tex]\frac{5}{7r}-\frac{2}{7r}[/tex]

You have two fractions with the same (common) denominator, so you subtract the numerators and put that over the common denominator.

[tex]\frac{5}{7r}-\frac{2}{7r}=\frac{5-2}{7r}=\frac{3}{7r}[/tex]