Original study example
With demand Qd = 100 - 2P and supply Qs = 20 + 2P, find equilibrium price and quantity.
Work through the example
Set demand equal to supply: 100 - 2P = 20 + 2P, so P = 20 and Q = 60. Substitute into both equations to check. Then explain how an increase in demand differs from a change in price along the original demand curve.