Based on last week's sales, a store manager concluded that by pricing the store's package of 12 12
donuts at $8
$
8
, the store will sell about 80
80
packages per day. Raising the price to $8.50
$
8
.
50
per package of 12
12
donuts will cause sales to fall to about 76
76
packages per day. If a linear model based on this data is used to predict the daily sales of y
y
packages of donuts when the price per package is x
x
dollars, which statement is true about the rate of change of this linear model?