Is this simultaneous equations?
if yes then the first step is
make one of the unknown as the subject
        
             
        
        
        
Answer:
7.1
Step-by-step explanation:
If you count how many units are between the library and the park, it is seven units.
 
        
                    
             
        
        
        
Since the equation for solving circumference is 2

r, you can see that 2

r = 46. Dividing 2

 on both sides will give you r, or the radius. 
Hope this helped! :)
 
        
        
        
X - height of the tree.
A proportion is:
1/2  : x = 1 : 36
x = 36 * 1/2
x = 18
Answer. the tree is 18 feet tall.