The problem concern the position vectors r1=2.43mi-4.74mj and r2=-3.02mi+0.85mj.
Find the angle between the two vectors. Hint: Find the angle each makes with the +x-axis.
There are several ways but the easy one is to do what the hint says:
tan x = -4.74/2.43
so first angle x = -62.86 degrees
tan y = .85/3.02
so y = 15.72
so 15.72 -(-62.86) = 78.58 degrees