High-low method; regression analysis. (CIMA, adapted) Anna Maitmez. thn financial manager at the Casa Real restaurant, is checking to see if there is any relationship between newspaper advertis- ing and sales revenues at the restaurant. She obtains the following data for the past 10 months: Month Revenues Advertising Costs March April Moy June July August September October November December 70,000 55,000 65,000 55,000 65,000 45,000 80,000 55,000 60,000 $2,000 3,000 1,500 3,500 1,000 2,000 1,500 4,000 2,500 2,500 . Use the high-low method to compute the cost function, relating advertising costs and revenues