How do you do the following?

A student wants to study the factors which affected the sales of cars by different manufacturers in the automobile industry across the world in the year 2017.? Generally, the sales of cars ?(?S, measured in? thousands) depend on the average price of the cars sold by the manufacturer ?(P?, measured in thousand? dollars), the average interest rate at which car loans were offered in that country in that year ?(?I, expressed as a? percentage), and the? manufacturers' total expenditure on the advertisement of their cars ?(E?, measured in thousand? dollars). She selects a random sample of 100 car manufacturers and estimates the following regression? function: