Calculating the shortage

The shortage can be calculated as follows. Set the price ceiling price equal to the demand equation and equal to the supply equation and solve for Q_d and Q_s respectively.

Demand	1 = 10 - 0.9Q_d
	Q_d = 10

Supply	1 = 0.5 + 0.5Q_s
	Q_s = 5.25

Subtracting Q_s from Q_d, we have a shortage of 4.75 units.