Help please math people

Find the sum to the equation 3+6+9+

Aregression was run to determine if there is a relationship between hours of tv watched per day (x) and number of situps a person can do (y). the results of the regression were: y=ax+b a=-0.662 b=30.418 r2=0.703921 r=-0.839

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.