Aline passes through the points (p, a) and (p, –a) where p and a are real numbers. if p=0, what is the y-intercept? explain your reasoning.

M = (y2 - y1) / (x2 - x1) 

Using (–12, 1.5), and (8, −3.5) 
m = (-3.5 - 1.5) / (8 - -12) 
m = -5/ 20 
m = -1/4 

Slope intercept form is 
y = mx + b 

Using point (8, −3.5) 
-3.5 = (-1/4)8 + b 
-3.5 = -2 + b 
b = -1.5 

Therefor 
y = (-1/4)x - 1.5