Let's assume that the total amount spent on the movie tickets and snacks is represented by x.
We know that:
The movie ticket costs $13.00
The drinks cost $6.00
Therefore, the equation representing the total amount spent is:
x = 13 + 6 + 4y
where y is the number of snacks purchased.
Let's substitute the given value of x:
23 = 13 + 6 + 4y
Subtracting 13 and 6 from both sides:
4 = 4y
Dividing both sides by 4:
y = 1
So, you purchased 1 snack.