a) [tex]2y^2+3b-2y-5b=2y^2-2y+3b-5b=\boxed{2y^2-2y-2b}[/tex]
b) [tex]3\left(x+y\right)-3y\left(y-x\right)=3x+3y-3y\left(y-x\right)=\boxed{3x+3y-3y^2+3xy}[/tex]
c) [tex]\frac{4x+12}{2}-\frac{3x-3}{3}=2\left(x+3\right)-\left(x-1\right)=2\left(x+3\right)-x+1=2x+6-x+1=2x-x+6+1=2x-x+7=\boxed{x+7}[/tex]
