The first step is to draw the coordinates in the cartesian plane:
Next you have to "Mirror" the points, this means, you check the distance over the X-axis and Y-axis for each point and then move to the next cuadrant and using those lengths you find the mirrored point:
So the mirroed ppoints are:
For A (-3,-6) is A' (3,-6)
For B (-5,-1) is B' (5,-1)
For C (-10,-9) is C' ()