Given:
Coordinates of point C are (-3,6).
Point B(0,5.5) is the midpoint of AC.
To find:
The coordinates of A.
Solution:
Let the coordinates of point A are (a,b).
Formula for midpoint:

Using the above formula, the midpoint of A(a,b) and C(-3,6) is


On comparing both sides, we get



and,




Therefore, the coordinates of point A are (3,5).