we know that E is in between 50,000 and 60,000. we substitute this in and find the values of s, which are 400,000 and 600,000. This becomes the domain therefore C is the answer.
50,000=0.05s+30,000
20,000=0.05s
400,000=s
60,000=0.05s+30,000
30,000=0.05s
600,000=s
since E is in-between $50,000 and $60,000, s is in between 400,000 and 600,000, which is the domain. C is the answer.
Hope this helps.