The domain is simply the list of all the inputs of the relation. So, the domain is the set on the left (Farenheit temperatures)
The range is the list of all possible outputs. So, it is the set on the right.
A relation is also a function is every input (i.e. every element of the domain) is mapped to one and only one output. Since this is the case (you never see more than one arrow starting from the same element on the left), this relation is actually a function.
