What is the domain and range of f(x)=4-x

Domain: Positive or Negative numbers
Range: 0
 

Domain is the numbers you can use for x
range is the numbers you get from inputing x

so we see that there aren't any values of x that make undefined things like division by 0 or square roots of negative numbers

so domain is all real numbers

we have a linear equation, so then it would be that the range is also all real numbers

domain is all real numbers
range is all real numbers