Answer
$$HX \gt HY \gt HZ$$
or
$$HZ \lt HY \lt HX$$
Work Step by Step
1. We can classify the basicity of the resulting solution with this order:
$$KZ \gt KY \gt KX$$
Because, with a greater pH, the solution is more basic.
2. Since the potassium ion does not affect the pH and since it does not hydrolyze, the other ions are the only thing affecting the basicity. Therefore, we can put them in order of basicity:
$$Z^- \gt Y^- \gt X^-$$
3. The weaker the acid, the stronger its conjugate base. Therefore, we have to reverse the order of strength to represent the conjugate acids:
$$HX \gt HY \gt HZ$$
