Find the zeros. In other words, when does y=0

Ineed if you could explain and give me the answer you! this needs done

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?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)