Blue Inc. is developing a forecasting model based on the perceived relationship between Sales and Marketing. Using the data below, apply the Linear Regression Method and c alculate the value of parameter a$.($Table shown in $ in thousands$).$ All calculations to $2$ decimal places.

$\backslash$table$[[$Sales$,$Marketing,,,$],[Y,x,xY,Y^2,x^{{?}^{{?}^{?}}2}$