Ineed asap will give ! the elevation of city a is 80 feet below sea level; the elevation of city c is 16 feet below sea level. the elevation of city d is 1 over 2 of the elevation of city c. part a: write an expression to represent the elevation, in feet, of city d. (5 points) part b: solve the expression and explain why the answer is negative or positive. (5 points)

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