If X is polynomial-time reducible to Y and X is polynomial-time reducible to Z then Y is polynomial-time reducible to Z?


If $ X$ is polynomial-time reducible to $ Y$ and $ X$ is polynomial-time reducible to $ Z$ ,
$ Y$ is polynomial-time reducible to $ Z$ ?

If $ X \leq_p Y$ and $ X \leq_p Z$ then $ Y \leq_p Z$ ?

True, false or we don’t know? Why?