"A billboard designer has decided that a sign should have 3-ft margins at the top and bottom and 5-ft margins on the left and right sides. Furthermore, the billboard should have a total area of 150 ft2 (including the margins)."

Ifx denotes the width (in feet) of the billboard, find a function in the variable x giving the area of the printed region of the billboard. Area, as a function of x = Determine the domain of the function for area. Enter your answer using interval notation. Domain of the function for area =