The equilibrium price would be when the Pdemand = Psupply. In this case the equilibrium price is 22 when the price per unit is 3.
Start by setting the equations equal to each other.
Solve for Q
Since a negative supply value doesn't make sense,
Plugging Q backing into the original 2 equations, we find that Pdemand and Psupply are both equal to 22.
Drawing a graph allows you to find the answer without the algebra by graphing both lines separately and finding the point of intersection.