\(a,=\dfrac{3x-3+4x+2+1-5x}{6x}=\dfrac{2x}{6x}=\dfrac{1}{3}\\ b,=\dfrac{x+y+2x-2y-3}{\left(x-y\right)\left(x+y\right)}=\dfrac{3x-y-3}{\left(x-y\right)\left(x+y\right)}\\ c,=\dfrac{4x-8-3x-6+12}{\left(x-2\right)\left(x+2\right)}=\dfrac{x-2}{\left(x-2\right)\left(x+2\right)}=\dfrac{1}{x+2}\)