I found width=13.72 ft and length=43.72 ft.
Call one dimension of the rectangle x, the other will be x+30
You want an area A=600 ft^2 but A=length x width=x*(x+30)=600
Rearranging you get:

solving this quadratic equation you get a negative solution and a positive one that gives your result.
In the y=mx+b format or a linear equation, this would be y=15x+25
Use Excel graphing. Then make histogram (a graph that represents values with columns)
C=(3.14)(15)
you multiply and get 47.1
Answer: 11
The code would print 11 as x=x-4 basically sets x to what x was and subtracts it by 4 which means 15 was its previous value and it takes 4 away from it so it is now 11. Then because the loop condition is x=11 the loop condition has been met and will now go and display x.