Answer: C. Their slopes are negative reciprocals
Step-by-step explanation:
The slopes of two perpendicular lines are negative reciprocals of each other.
 
        
             
        
        
        
If the cell phone company charges a flat $40 fee monthly, then the equation would be y = 40. 
The company does charge $40 a month, but also charges $2 per minute out of service area (x). 
So the equation is y = 2x + 40
To graph this linear function, plug in values for x then plot the plots. Then draw a line to connect the points. 
y = f(x)
f(0) = 40
f(1) = 42
f(2) = 44
f(3) = 46
f(4) = 48
f(5) = 50
So at x=0, draw a point at y=40 and so on. 
        
             
        
        
        
Flipping a coin should be it