Answer
$\dfrac{3x^2+6x-2}{(x+5)(x+2)}$
Work Step by Step
Let's note:
$$E=\dfrac{3x}{x+5}-\dfrac{2}{x^2+7x+10}.$$
First we factor denominators:
$$E=\dfrac{3x}{x+5}-\dfrac{2}{(x+2)(x+5)}.$$
The Least Common Denominator is $(x+2)(x+5)$. We multiply the first fraction by $\dfrac{x+2}{x+2}$:
$$E=\dfrac{3x(x+2)}{(x+5)(x+2)}-\dfrac{2}{(x+5)(x+2)}.$$
Perform subtraction:
$$\begin{align*}
E&=\dfrac{3x^2+6x-2}{(x+5)(x+2)}.
\end{align*}$$
