# Write a function to convert degrees Fahrenheit to degrees Celsius: to_celsius
def to_celsius(F):
    return 5/9*(F - 32)

# Apply the function over 'Mean TemperatureF' and 'Mean Dew PointF': df_celsius
df_celsius = to_celsius(F=weather[['Mean TemperatureF','Mean Dew PointF']])

# Reassign the columns df_celsius
df_celsius.columns = ['Mean TemperatureC', 'Mean Dew PointC']

# Print the output of df_celsius.head()
print(df_celsius.head())
