Explanation:
If 15% of the dice in the variety-pack are red, then the proportion of red dice to total dice is 0.15.
Let's represent the number of red dice as "x".
We know that the total number of dice in the pack is 20. Therefore, the number of non-red dice must be 20 - x.
We can set up an equation using the proportion of red dice:
x/20 = 0.15
To solve for x, we can multiply both sides by 20:
x = 20 * 0.15
x = 3
Therefore, there are 3 red dice in the pack.