## Algebra and Trigonometry 10th Edition

$a.) m=135$ $b.) m=0$ $c.)m=-40$
$a.) m=135.$ The sales are increasing at a rate of 135 units per year. $b.) m=0.$ There is no change in sales during the year. $c.) m=-40.$ The sales are decreasing at a rate of 40 units per year.