Think of domain as how far the graph expands on the x-axis as asymptotes as the limits. So in this case, the graph extends infinitely on the x-axis; so it should be all real numbers.
If 3mile=28 min x mile=42 min cross multiply x=3/28 therefore if 3/28=1 min then x mile= 42 min cross multiply 42 x 3/28 =21 x 3/14 =3 x 3/1 =9 The answer is 9 miles
