To find the absolute value of a number find the distance from zero and write the distance as a negative integer

Consider the reflection of parallelogram pqrs across the line of reflection, . if rr' = 14, then rz = . if sx = 5, then = 5.

Consider the set of all four-digit positive integers less than 2000 whose digits have a sum of 24. what is the median of this set of integers?

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.