A pizza is cut into six unequal slices (each cut starts at the center). The largest slice measures 90 degrees:
If Larry eats the slices in order from the largest to the smallest, then the number of degrees spanned by a slice decreases at a constant rate. (So the second slice is smaller than the first by a certain number of degrees, then the third slice is smaller than the second slice by that same number of degrees, and so on.)
What is the degree measure of the fifth slice Larry eats?
Explain your reasoning in complete sentences.