Triangle ABC is isosceles with point A at the point (2, 7), with point B at (-2,0) and with point Cat (3,-1). Triangle ABC is reflected over BC to form AA'BC. Triangle ABC is reflected over A'C to form AA'B'C. Triangle A'B'C' is reflected over B'C' to form AA" B'C. What is the slope of A" A? Express your answer as a common fraction.