Formula:

Celsius = (Fahrenheit - 32) * 5/9

Calculation:

1. Start with the Fahrenheit temperature: 77°F

2. Subtract 32: 77 - 32 = 45

3. Multiply by 5/9: 45 * (5/9) = 25

Answer: A room temperature of 77 degrees Fahrenheit is equal to 25 degrees Celsius.