How to do two step equations wit subtraction

Jackie purchased 3 bottles of water and 2 cups of coffee for a family for $7.35. brian 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? i need this done

Tyler enjoys the fish so much that after his birthday his family decides to take him to a famous aquarium a tank at the aquarium is similar to his tank with the scale factor of 8 how many times greater is the volume of the tank at the aquarium than the volume of tyler tank

Graph the equationy=x^2 -[tex]y = x^{2} - 2[/tex]