Yes. This is because if you plot the numbers on a ration table or see the graph points, you can see a pattern: you multiply by 5. The equation to solve this would be y=5x. Another reason why this is proportional is that the graph starts from the origin (0,0) This is the opposite for non-proportional relationships. Hope this helps! :)
87 degrees minus 10 degrees would give you 77 (which is the lowest temperature). then 77 degrees plus 17 degrees is 94 degrees. the difference between the highest temp and lowest (94-77) would be 17.
