There were 166 telephones for every 100 people what is the ratio of phones to people

Given right triangle xyz, which correctly describes the locations of the sides in relation to

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

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