To determine the probability of something, count the total of how much of a certain thing you are looking for, and then put it over the total.
With this information, we can now figure out the answer.
We have 6 vanilla cookies and 24 cookies total.
Put the amount of what we are looking for over the total as a fraction.
6/24 is our fraction.
To ensure a correct and proper answer, we need to verify for simplification of the fraction.
If both numbers are even, try to divide by 2.
Both of our numbers are even, so divide them by 2.
6/2 = 3
24/2 = 12.
Our new fraction is 3/12.
Since our numerator is prime, let's try to divide both numbers by it to ensure simplification.
3/3 = 1
12/3 = 4.
Your new and simplified answer is 1/4.
I hope this helps!