[tex]\frac{19}{4}rs -\frac{8}{3}r^2+\frac{1}{4}rs +9[/tex]
The only like terms are 19/4rs and 1/4rs because they have the same variables, so: [I rearranged, to put the like terms next to each other]
[tex]-\frac{8}{3}r^2+\frac{19}{4}rs+\frac{1}{4}rs+9[/tex] Since the denominators are already the same, you can combine the fractions
[tex]-\frac{8}{3}r^2+\frac{20}{4} rs+9[/tex]
[tex]-\frac{8}{3} r^2+5rs+9[/tex]
