calculus - Continuous function with a point of periodicity

I have trouble in following question.

Suppose $f : [a, b] \to [a, b]$ is continuous and $x_0$ is a point having period $3$. How many points of period $5$ are there? How many orbits of period $5$? How many points of period $29$ are there?

I think there should be a specific function so that we can check the periodicity, but apparently there's anything wrong in this wording of this problem according to class. Could anyone give me the clue? Might be bifurcation?