Step-by-step explanation:
the slope of the line between the first 2 points must be the same as the slope between the second and the third point.
the slope is y difference / x difference.
so,
b/a = d/c
-3/1.6 = d/1.5
d = -3×1.5 / 1.6 = -4.5 / 1.6 = -2.8125
