Denise and Aaliyah had lunch at the mall. Aaliyah ordered three slices of pizza and two waters. Denise ordered two slices of pizza and three waters. Aaliyah's bill was $6.00, and Denise's bill was $5.25. What was the price of one slice of pizza? What was the price of one water?

Liana spent $131 on shirts. Fancy shirts cost $28 and plain shirts cost $15. If she bought a total of 7 shirts then how many of each kind did she buy?

Mr. Velazquez purchased two donuts and three cookies and is charged $3.30. Ashley purchases five donuts and two cookies for $4.95 at the same shop. Find the cost of one donut and one cookie.