Answer:
1.5 and -1.5
Explanation:
The coordinate of A is 0. It is given that AR = 3. AR represents the distance from point A to point R. Remember that distance is always positive. So, from here we have two possibilities.
- Point R is on Right side of A i.e. at coordinate 3
- Point R is on Left side of A i.e. at coordinate -3
In both of these cases AR which is the distance from A to R will be 3.
So, if R is on Right side of A, the midpoint of AR would be:

Or if R is on Left side of A, the midpoint of AR would be:

Thus, the possible coordinates of the midpoint of AR are 1.5 and -1.5