Answer:
cross price elasticity formula:
Exy = % change in quantity demanded of X / % change in price of Y
E(penguin patties, frizzles) = 0.05 / 0.04 = 1.25 ⇒ SUBSTITUTE GOODS
E(penguin patties, mookies) = -0.04 / 0.04 = -1 ⇒ COMPLEMENTARY GOODS
When two goods have a positive cross price elasticity, it means that they are substitute and an increase in the price of one of them will result in an increase in the quantity demanded of the substitute one. When two goods have a negative cross price elasticity, it means that they are complements, meaning that an increase in the price of one good will result in the decrease of the quantity demanded of both goods.
The company should market penguin patties along with mookies since they are complements.