What is the value of x? ma3110 b unit test

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

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

Which coefficient matrix represents a system of linear equations that has a unique solution ? options in photo*