Let x = number of batches.
So for every batch, you need 2 cups of flour, and you have 20 cups of flour. You cannot make a batch if you don't have the sufficient amount. So using our information, our inequality is
. However, this can be further simplified.
For this inequality, divide both sides by 2, and your inequality is
. In context, you can make up to 10 batches of cookies.