Answer: 21x4=84units
Step-by-step explanation:
Well, if the perimeter is 28, then 28/4=7units, is each side of the square. Right? So, if we scale it up by a factor of 3, or 7 x 3=21 units, the side of the new square. Therefore 21 x4 =84units, the perimeter of the new square.
