Which of the following pairs of goods are complements, which are substitutes, and which are unrelated? Which of the following pairs of goods are complements, which are substitutes, and which are unrelated? We observe the price of Pepsi increases and the quantity demanded of Coca-Cola increases: A smartphone and smartphone apps: substitutes Tide laundry detergent and Cheer laundry detergent: unrelated complements You observe that your significant other always adds 1 oz of cream to each cup of coffee