Finding the Total Cost of Drinks

Two store owners, Maya and Sam, are selling sports drinks. Maya sells 3 drinks for $9, while Sam sells 5 drinks for $15. The prices of the drinks can be represented with the following systems of equations:

Equation 1: Let $x$ be the price of one drink at Maya's store, so $3x = 9$

Equation 2: Let $y$ be the price of one drink at Sam's store, so $5y = 15$

What is the total cost of buying one drink from both Maya’s and Sam’s stores?