Math genius help me please

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?

Just tell me how to set up the equation.

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base