we have M is durectly porpotional to r^2
so M=(k)r^2
and when r=2, m=14
so 14=(k)(2)^2
k=14/4 =7/2
so when r=12
m= (7/2)(12)^2 =(7/2)(144) = 504
The price is a linear growth and the constant growth rate is $0.65. To get that as the constant I subtracted 13.25 and 6.75 to get 6.5. After subtracting, I divided 6.5 by 10 to get .65 or $0.65.
Sent a picture of the solution to the problem (s). Just rotate pic.