Answer:
The correct answer is: increase; decrease.
Explanation:
According to the demand theory if the price of a good increases the quantity demanded decreases. If the price of the good decreases, the quantity demanded increases. We can say then that the relationship between the price and the quantity demanded is inversely proportional.
In that case, if peanut butter and jelly are usually sold together and the price of jelly increases, so will the price of the peanut butter. Thus, the quantity demanded of both the peanut butter and jelly will decrease.
