A temperature of 41 degrees F is equivalent to 278.2 degrees K, while a temperature of 86 degrees F is equivalent to 303.2 degrees K. Find the equation converting Kelvin temperature to Fahrenheit. What is the Fahrenheit temperature when it is 180 degrees K?

on converting fahrenheit to celsius then to kelvin.
C=(F-32)*(5/9)
K=C+ 273.15

How are they getting the answer 273.15?