Seth is paid on a graduated commission scale. He earns 10% commission on is first $1,000 in sales. He earns 15% commission on all sales over $1,000. Last month, his total sales were $2,500. What was his total commission?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters