A producer of athletic shoes produces all of its basketball

A producer of athletic shoes produces all of its basketball shoes at a constant marginal cost of $50 per pair. It sells a brand-name version of the shoe with a basketball star endorsement to one market (A) and an identical “discount” brand version to another separate market (B). The demand for the shoes in each market is given by:

QA = 100 – 0.2p
QB = 40 – 0.4p

• What is the price per pair in the brand-name market (A) dollar?
• What is the price per pair in the discount market (B) dollar?