Rectangle j’k’l’m location of u

Jackie purchased 3 bottles of water and 2 cups of coffee for the family for $7.35. ryan bought 4 bottles of water and 1 cup of coffee for his family for 7.15. how much does each bottle of water cost? how much does each cup of coffee cost?

We just started the introduction into circles and i have no idea how to do this.

Which describes the difference between the graph of f(x)=x^2 and g(x)=-(x^2-2)