Consider the following data:

A retail chain will buy 900 cordless phones if the price is $10 each and 400 if the price is $60. A wholesaler will supply 700 phones at $30 each and 1400 at $50 each.

Let us find the market equilibrium point assuming that the supply and demand functions are linear.

Convert the information in the above data into the table as follows:

Demand Quantity	Price	Supply Quantity	Price
900	10	700	30
400	60	1400	50

First we create the demand function.

For this, enter the data of demand quantity and price from the table in the lists of a graphing utility.

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

The demand function, 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 demand function is.