A pack of paper costs $3.75, including tax. Mr. Cooper wants to purchase packs of paper for his class and has a $20 budget. Write an inequality to solve for the number of packs of paper Mr. Cooper can purchase.

$3.75x ≥ $20
$3.75x ≤ $20
$20x ≤ $3.75
$20x ≥ $3.75