To determine how many bags Damari needs to sell, we can subtract his current money from his goal money and divide by the cost of one bag of popcorn.
Goal money - Current money = Money needed to earn
$85 - $40 = $45
Money needed to earn / Cost of one bag = Number of bags needed to sell
$45 / $3 = 15
Therefore, Damari needs to sell 15 bags of popcorn to make his goal.