Supply and demand mastery
Equilibrium, shocks, and surplus reasoning for contests.
Core model
Price coordinates buyers and sellers. Equilibrium is where Qd = Qs. Surplus means price is above equilibrium; shortage means below.
Curve shifts
Demand shifts with income, tastes, prices of substitutes, expectations. Supply shifts with input costs, technology, number of sellers, taxes/subsidies.
Move along a curve = price change; shift = non-price determinant.
Welfare
Consumer surplus is area below demand above price; producer surplus is above supply below price. Deadweight loss appears when quantity is restricted (tax wedge, monopoly, quota).