Formula:

Celsius = (Fahrenheit - 32) * 5 / 9

Calculation:

1. Subtract 32 from the Fahrenheit temperature: 41.9 - 32 = 9.9

2. Multiply the result by 5: 9.9 * 5 = 49.5

3. Divide the result by 9: 49.5 / 9 = 5.5

Therefore, 41.9 degrees Fahrenheit is equal to 5.5 degrees Celsius.