Three times the sum of a number and twelve i do not know how to write that

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?

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

Your car's gasoline tank holds 18 gallons of gasoline. on a trip in canada, the tank is one-quarter full. you want to fill the tank. how many liters of gasoline are needed to fill the tank