The points are evenly spaced at a distance of 15 units between each other, then when we go to the right side of the graph from 0 we increase 15 units until we reach the point E, 15 units further we get to the point F, then we have the following labels:
E = 15
F = 15 + 15 = 30
As we got the left side from 0, we subtract 15 units for each marking, then we get:
D = 0 -15 = -15
C = -30 -15 = -45
B = -45 - 15 = -60
A = -60 - 15
