It takes Brenda the same amount of time to run 3/4 run of a mile as it does for Megan to run 4/5 of a mile. At these rates, what fraction of a mile will Brenda have run by the time Megan has run a full mile?

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