Your tool of choice here will be the equation that establishes a relationship between temperature expressed in Kelvin and temperature expressed in degrees Celsius
#color(blue)(ul(color(black)(T["K"] = t[""^@"C"] + 273.15)))#
You can rewrite this equation to find the temperature in degrees Celsius
#color(blue)(ul(color(black)(t[""^@"C"] = T["K"] - 273.15)))#
Plug in your value to find
#t = "450 K" - 273.15 = color(darkgreen)(ul(color(black)(177^@"C")))#
The answer must be rounded to zero decimal places, the number of decimal places you have for the temperature in Kelvin.