Question

Supply = -20+10p
Demand = 400-20p
Solve for equilibrium price and quantity

Answer 1

To calculate equilibrium price equate the supply equation to the demand equation and solve for p

$$-20+10p=400-40p$$

$$50p=420$$

$$p=8.40$$

To get equilibrium quantity substitute 8.40 for p in either equation

$$400-40\times8.4=64$$