This is an altitude.  Shown by the right angle on the side opposite the point.
        
                    
             
        
        
        
Insert x = -1 and y = 4 into the first inequality:-
4 <= -(-1) + 4 = 5  
so this fits
Its A
        
                    
             
        
        
        
subtract r from c to get 8x+10
 replace x with 3
8(3) +10 = 34 which in hundreds is 3400 dollars
the answer is C