To convert degrees Fahrenheit to Kelvins you need to add 459.67 to degrees Fahrenheit multiply the result by 5 and divide it by 9.
With 77 °F you have: ((77 + 459.67) × 5) ÷ 9 = (536.67 × 5) ÷ 9 = 2683.35 ÷ 9 = 298.15 K