Describe equilibrium price and quantity

Question

Assume the market for widgets can be described by the given equations:
                     Demand: P = 10 - Q               Supply: P = Q - 4
Here P refers to the price in dollars per unit and Q refers to the quantity in thousands of units.
Describe equilibrium price and quantity?
To determine the equilibrium price and quantity, equate supply and demand and solve out for Q_EQ:
                                                         10 - Q = Q - 4, or Q_EQ = 7.

Substitute Q_EQ in either the demand equation or the supply equation to get P_EQ.
                                                           P_EQ = 10 - 7 = 3,
                                                                            or
                                                           P_EQ = 7 - 4 = 3.