To represent the cost of a drink, we can complete the equation as follows:
\( x + 3.19 = 5.61 \)
Now, we can solve for \( x \):
- Subtract \( 3.19 \) from both sides:
\[ x = 5.61 - 3.19 \]
- Calculate the right side:
\[ x = 2.42 \]
So, the completed equation and the solution for the cost of a drink is:
\( x + 3.19 = 5.61 \)
\( x = 2.42 \)