All ratios equivalent to 6:3

What could explain what happened when the time was equal to 120 minutes

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

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.