What is the difference in the discount rate between Bell Wireline and Bell Media?
{"Bell Wireless": {"PERPETUITY GROWTH RATE": 0.8, "DISCOUNT RATE": 9.1}, "Bell Wireline": {"PERPETUITY GROWTH RATE": 1.0, "DISCOUNT RATE": 6.0}, "Bell Media": {"PERPETUITY GROWTH RATE": 1.0, "DISCOUNT RATE": 8.0}}
bell_media_discount_rate = df["Bell Media"]["DISCOUNT RATE"]
bell_wireline_discount_rate = df["Bell Wireline"]["DISCOUNT RATE"]
answer = bell_media_discount_rate - bell_wireline_discount_rate