drawing a slope in random circles python

So my program is designed to manipulate certain coordinates in order to create this image:

So basically my program draw a bunch of random circles and I have to manipulate the line of equation to create the red sections. So far my image is the following:

I can't seem to figure out how to add another line equation to create the other red section. Any help would be greatly appreciated!

# using the SimpleGraphics library
from SimpleGraphics import *

# tell SimpleGraphics to only draw when I use the update() function
setAutoUpdate(False)


# use the random library to generate random numbers
import random


# size of the circles drawn
diameter = 15

resize(600, 400)


##
# returns a vaid color based on the input coordinates
#
# @param x is an x-coordinate 
# @param y is a y-coordinate 
# @return a colour based on the input x,y values for the given flag
##
def define_colour(x,y):
  ##
  #add your code to this method and change the return value
  slopeOne = (200 - 300)/(0-150)
  b = 0 - (slopeOne * 200)
  #slopeTwo = (0-150)/(200 - 300)
  #b = 200 - (slopeOne * )



  lineEquationOne = (slopeOne * x) + b
  #lineEquationTwo = (slope * x) + b

  if y > lineEquationOne:
    return "white"
  else:
    return 'red'





######################################################################
#
# Do NOT change anything below this line
#
######################################################################

# repeat until window is closed
while not closed():
  for i in range(500):
    # generate random x and y values 
    x = random.randint(0, getWidth())
    y = random.randint(0, getHeight())

    # set colour for current circle
    setFill( define_colour(x,y) )

    # draw the current circle
    ellipse(x, y, diameter, diameter)

  update()