Please help due tomorrow

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

Afamily went out to dinner and their bill was $113.if they want to leave a 19% tip, how much should they leave.

Interpret the following expression (5y^2-7)^3/(2y)^2