Let's define the following variables.
x = the number of gallons of Bryers ice cream Tanya bought
y = the number of gallons of Turkish Hill ice cream Tanya bought
2x = total cost for the Bryers ice cream
3y = total cost for the Turkish Hill ice cream
Since Tanya bought a total of 10 gallons of ice cream for the party, then we can say that:
In addition, if the total cost that Tanya spent is $25, then we can say that:
The equations that we can get from the given problem are x + y = 10 and 2x + 3y = 25.