Consider that the table below gives the quantity of the graphing calculators demanded and the quantity supplied for selected prices.

Price ($)	Quantity Demanded (thousands)	Quantity Supplied (thousands)
50	210	0
60	190	40
70	170	80
80	150	120
100	110	200

(a) Let us find the linear equation that gives the price as a function of the quantity demanded.

Enter the data of price and quantity demanded from the above table in the lists of a graphing utility.

The figure below shows a partial list of the data points.

The linear equation that gives the price as a function of the quantity demanded, found using linear regression with a graphing calculator.

The linear equation with price p as a function of the quantity demanded q is Thus, the linear equation is.