Answer
(a) $f(5)=1$
(b) $f(-5)=-1$
Work Step by Step
RECALL:
$f(a)$ represents the value of the function $f$ when $x=a$.
Replace $x$ with the given value to obtain:
(a)
$f(5) = \dfrac{|5|}{5}
\\f(5)= \dfrac{5}{5}
\\f(5)=1$
(b)
$f(-5) = \dfrac{|-5|}{-5}
\\f(5)= \dfrac{5}{-5}
\\f(-5)=-1$