The value of "b" is the y-intercept.
In order to figure out slope-intercept form you need 1 coordinate and the slope. 
1) Find the slope, using the 2-point slope formula: "m= y2-y1 / x2-x1".
   ex. m= -5 - 3 / -4 - -6   (simplify)--->   m= -4
2) Fill in the blanks for point-slope formula: "y - y1 = m (x - x1)"
(choose one coordinate, it doesn't matter which one)
   ex. y - -5 = -4 (x - -4)
3) Then use basic algebra to simplify.
        
             
        
        
        
It’s $15.69 for each of the 3 pizzas because 15.69+15.69+15.69=47.07 and then add the delivery fee and it’s 49.57
        
                    
             
        
        
        
It should be :
1/3(x + 18) = 7
1/3x + 6 = 7
1/3x + 6 - 6 = 7 - 6
1/3x = 1
x = 3
        
                    
             
        
        
        
Answer:
This answer would be c
Step-by-step explanation: