Final answer:
The expression that represents the number of packages Dirk bought is b / 4.
Step-by-step explanation:
To determine how many packages of breadsticks Dirk bought, we need to divide the total number of breadsticks by the number of breadsticks in each package.
Since Dirk has b breadsticks and each package has 4 breadsticks, the expression that represents the number of packages Dirk bought is: b / 4