The trend line of a product's sales is $y = 85 - 2.5x$, with $x$ in years. What does it say?

Explanation

1. 01

   The slope is the change in $y$ for each year.

2. 02

   $-2.5$ means the trend falls by 2.5 units a year; 85 is the trend value at $x = 0$.