To find the cost of the drink \( x \), we start with the equation that represents the total cost of a slice of pizza and a drink.
The cost of a slice of pizza is $3.19, and together with the drink (which costs \( x \)), the total is $5.61.
So, we can set up the equation:
\[ x + 3.19 = 5.61 \]
Now, we solve for \( x \):
- Subtract $3.19 from both sides:
\[ x = 5.61 - 3.19 \]
- Calculate the right side:
\[ x = 2.42 \]
Thus, the completed equation and the solution are:
\[ x + 3.19 = 5.61 \]
\[ x = 2.42 \]
So, the cost of the drink is $2.42.