Answer:
The price of the cereal boxes
Step-by-step explanation:
 
        
                    
             
        
        
        
It does match-
The Y-Intercept is 12
And the slope is -3/1
You can confirm this by counting rise over run in the graph 
Starting at the Y-Intercept (Y=12) the graph goes down 3 units (-3) over 1 unit (1) 
This confirms that the slope is -3/1
        
             
        
        
        
When x=0 y=50 when y=0 x=+\-5. -x^2 makes the parabola open downward y(x)=2x^2+50;y(3)=2*9+50=32
        
             
        
        
        
Since the change is to x, it will be a horizontal transformation.
When x is multiplied by a factor between 0 and 1, it stretches the function horizontally.
In this case, it stretches the function by a factor of 2 horizontally.