A financial analyst is examining the relationship between various factors affecting the annual sales revenue ($Y$) of a retail store. To quantify this relationship, they decide to conduct a multiple regression analysis that includes three independent variables: advertising expenditure ($X_1$), number of store promotions ($X_2$), and average store foot traffic ($X_3$). The regression equation is given by:
$$ Y = eta_0 + eta_1X_1 + eta_2X_2 + eta_3X_3 + ext{error} $$
The analyst obtains the following coefficients from the regression output:
If the store invests $1000 in advertising, implements 10 promotions, and attracts 2000 customers, what is the estimated annual sales revenue?