If I'm reading the question right, you have
[tex]f(x)=\begin{cases}x-3&\text{for }x<5\\2&\text{for }5\le x\le6\\x+4&\text{for }x>6\end{cases}[/tex]
and you have to find
[tex]\displaystyle\lim_{x\to5}f(x)\text{ and }\lim_{x\to6}f(x)[/tex]
The limits exist if the limits from either side exist. We have
[tex]\displaystyle\lim_{x\to5^-}f(x)=\lim_{x\to5}(x-3)=2[/tex]
[tex]\displaystyle\lim_{x\to5^+}f(x)=\lim_{x\to5}2=2[/tex]
[tex]\implies\displaystyle\lim_{x\to5}f(x)=2[/tex]
and
[tex]\displaystyle\lim_{x\to6^-}f(x)=\lim_{x\to6}2=2[/tex]
[tex]\displaystyle\lim_{x\to6^+}f(x)=\lim_{x\to6}(x+4)=10[/tex]
[tex]\implies\displaystyle\lim_{x\to6}f(x)\text{ does not exist}[/tex]