Add the following expressions and simplify if possible:
$\frac{x}{x^2+3x}+\frac{3}{x+3}$

Add the following expressions and simplify if possible:

$\frac{2}{x^2-1}+\frac{3}{x+1}$

Add the following expressions and simplify if possible:

$\frac{x^2}{x^2-4}+\frac{2x}{4-x^2}$

Subtract the following rational expressions and write the difference in simplest form if possible.

$\frac{3}{x}-\frac{2}{x+2}$

Subtract the following rational expressions and write the difference in simplest form if possible.

$\frac{x+2}{x^2-4}-\frac{1}{x-2}$

Subtract the following rational expressions and write the difference in simplest form if possible.

$\frac{x^2}{x^2-25}-\frac{5x}{25-x^2}$