Larger by 3 means that the legnths of the sides are larger by 3 times so we have a cube that has area of 400 surface area=legnth times width times 6 since it is a cube and legnth=width so SA=w^2 times 6
6w^2=400 divide by 6 w^2=200/3 square root both sides w=√(200/3) so w is 3 times larger (3w)^2 times 6 is new area
w=√(200/3) (3√(200/3))^2 times 6=9(200/3) times 6=600 times 6=3600
