(x^2+9x)/(x^2+3x)+(x^2-9)/(x^2+6x+9)
=x(x+9)/x(x+3)+(x+3)(x-3)/(x+3)^2
=(x+9)/(x+3)+(x-3)/(x+3)
=[(x+9)+(x-3)]/(x+3)
=(2x+6)/(x+3)
=2