Please answer them all if you can:)

8000 + 8800 + 8000 + 8 million + 80 trillion + another a katrillion equals

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

Math i have no idea how to do a and b