#### Answer

a=-2 and 8

#### Work Step by Step

As we know that the pair of points have x coordinate common so the distance between the two points can be found by getting the absolute value of the difference between the two non common coordinate points.
Therefore, |3-a|=5
|x| =a so it can be x=-a or x=a
|3-a| = 5
so, 3-a = 5 or 3-a = -5
3-5=a or 3+5 =8
-2 = a or 8 =a
Therefore the possible values of a are -2 and 8.