A student is making two types of wallets out of duct tape. She is going to make a tri-fold wallet and a bi-fold wallet. The tri-fold wallet takes 1 hour to finish and the bi-fold wallet takes 2 hour to finish. Each tri-fold wallet costs $1 to make and each bi-fold wallet costs $0.75 to make. The tri-fold wallet sells for $10 and the bi-fold wallets sell for $8. If the student has at most $24 to purchase materials and no more than 20 hours throughout the week to make wallets, what combination of tri-fold and bi-fold wallets should she make and sell to maximize profit?