This is a fraction that has a linear expression as the numerator and a constant number in denominator.
So we can simply divide each term of numerator by denominator because we can write [tex] \frac{a+b}{c} = \frac{a}{c}+ \frac{b}{c} [/tex]
So we can write given fraction as
[tex] \frac{2m-5}{9} = \frac{2m}{9} - \frac{5}{9} [/tex] which is expressed as a difference.