Answer: $75/hour
0 hours of labor = just the evaluation fee
2 hours of labor = 165, which is the evaluation fee plus 2 x hourly labor
So if h is hourly rate for labor,
2h + 15 = 165
2h = 150
h = 75
We can check that equation with the next pair of numbers as well
4h + 15 = 315
4h = 300
h = 75
Let me know if you have questions.