D=5.4 ft circumference

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

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

3x + 4y = 5 x- 3y = -7 solve by substitution