You consider each parittion of the axis represents 1 unit.
You can notice that in the given image, the coordinates of the points A, B, C and D are the following:
A(-6,4)
B(-2,1)
C(2,3)
D(-1,-4)
where you have taken into account that point left side of the origin have negative x valuesand points right side have positive x values. Point down side of origin have negative y values and points above origin has positive y values.