Due to the nature of spheres, they are all similar to each other.
Y= -5/3x + 2
To find slope:
-8-7 / 6 - (-3) = -5/3
Plug in x and y from one of the points to the equation to find b
7 = -5/3 (-3) + b
B = 2
Put it all together:
y = -5/3x + 2

notice, Papa Bear is 18inches in diameter, but radius is half that
and "edge per dollar" simply means, how much circumference per dollar
or
The equivalent decimal is 61.(3)