How much did the foreign exchange rate changes impact percent change in revenue?
{"Revenue": {"Percent change compared to prior fiscal year (as reported)": 25, "Constant currency percent change compared to prior fiscal year (1)": 24, "Positive/negative/neutral impact from foreign exchange rate changes": "Positive"}, "Total spend": {"Percent change compared to prior fiscal year (as reported)": 1, "Constant currency percent change compared to prior fiscal year (1)": 1, "Positive/negative/neutral impact from foreign exchange rate changes": "Neutral"}}
revenue_percent_change = df["Revenue"]["Percent change compared to prior fiscal year (as reported)"]
fx_rate_percent_change = df["Revenue"]["Constant currency percent change compared to prior fiscal year (1)"]
answer = revenue_percent_change - fx_rate_percent_change