Elimination Method:

The demand and supply of system of equations are

                                       (Demand equation)

                                       (Supply equation)

Where p is the price in dollars and x represents the number of units.

The equilibrium point is the price p and number of units x that satisfy the both demand and supply equations.

Because p is written in terms of x, the value of p substitute in the supply equation into the demand equation as follows:

                                        (Write demand equation)

                        (Substitute )

                                    (Add 0.4x to each side)

                                              (Subtract 380 from each side)

                                                    (Divide each side by 0.5)

Now, find the p value by substitute in either equations.

                                        (Supply equation)

                                (Substitute )

                                       (Simplify)

To check the solution substitute in the demand equation.

                                        (Write demand equation)

                                (Substitute )

                                            (Multiply)

                                       (Simplify)

To check the solution substitute in the demand equation.

                                        (Write supply equation)

                                (Substitute )

                                            (Multiply)

                                        (Simplify)

So the equilibrium point is .

The equilibrium point is .