The study on Price ($) and Sales of automobiles resulted in the following data: Use the following formula to calculate the correlation r between the Sakes (Y) and the price (X) in the table below:

Price (X)		10	20	30	40	50	60	70	80	90	100
Sales (Y)		28	25	25	19	15	12	9	10	6	5

Use the variables and numbers in the table above to calculate the equation of the regression line:

is the predicted value of y (Sales) using x (Cost) with b_o (the sample intercept) and b₁ (the sample slope).

A. Calculate b₁

B. Calculate b₀

C. Write the equation of the regression line :

D. What is the estimated value, for x = 15?

Please type yourself, not in paper.