Arlene found the markers she needed for a project at an art store. The store sold a pack of 5 markers for $2.99, a pack of 10 markers for $5.49, a pack of 20 markers for $9.00, and a megapack of markers that had 50 markers for $20.00. Arlene bought the pack of markers that cost $0.45 per marker. Which pack did Arlene buy?
