[tex]\bf \begin{cases}
c(x)=\cfrac{5}{x-2}\\
d(x)=x+3\\
----------\\
(cd)(x)\iff c(x)\cdot d(x)
\end{cases}\implies \cfrac{5x+15}{x-2}[/tex]
the domain, or safe values "x" can take on, are values, that do not make the fraction undefined, and that happens, when the denominator is 0
well, take a look at the denominator, what values of "x", make x-2 end up as 0?