Please help I’m not sure how to do this.

Marquise has 200 meters of fencing to build a rectangular garden. the garden's area (in square meters) as a function of the garden's width w w (in meters) is modeled by: a ( w ) = − w 2 + 1 0 0 w a(w)=−w 2 +100w what side width will produce the maximum garden area? meters

Need plz been trying to do it for a long time and still haven’t succeeded

How many square centimeters of wrapping paper will be used to wrap the shoe box?