Final answer:
Joy's error in determining the slope of the line is that she incorrectly calculated the rise and run of the line.
Step-by-step explanation:
Joy's error in determining the slope of the line that passes through the points (-6,33) and (6,-27) is that she has incorrectly calculated the rise and run of the line. To find the slope, we use the formula: slope = (change in y-coordinate) / (change in x-coordinate). Therefore, the slope is calculated as follows:
slope = (-27 - 33) / (6 - (-6)) = (-60) / (12) = -5
So, the correct slope of the line is -5, not -1/5 as Joy claimed.