What is the slope of the linear equation y=-2+6

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

How to simply and write the answer n a whole number

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18