Answer
$f(25)=2$
Work Step by Step
Having a period of $10$ ,means that the value of the function repeats (or the same) for every interval of $10$.
Thus, if $f(x) = a$, then $f(x+10)=a$, $f(x+20)=a$, $f(x+30)=a$, and so on.
This means that the value of the function will always be $a$ when a multiple of $10$ is added to $x$.
Since the period of the given function is $10$, and $f(5)=2$, then $f(25)=2$.
