The linear function
y
=
2
x
+
25
models the average cost of a haircut in a certain city, where
y
, is the average price of a haircut
x
years after 1985. Find the slope for the model. Then describe what this means in terms of the rate of change in the average cost of a haircut over time.
a)
m
=
2

b) The average cost of a haircut in this city increased (Enter: increased or decreased or not changed ) at a rate of per year after 1985.