This is what we know:
The ratio of strawberry to banana batter is 2:3.
The total amount of batter is 30 cups.
We add the ratio amount, which equals to 5, and then divide the amount of cups (30) by the ratio amount (5). This equals to 6 cups, meaning that every 'ratio number' will be equal to the value of 6 cups. Now, we multiply 6 by the amount of banana batter, which equals to 18 cups. Answer= 18 cups.