<h3>
Answer: 35 inches</h3>
Each side of the pentagon is multiplied by 5/3 to get the length of each new side, so the perimeter is multiplied by 5/3 to get the new perimeter.
New perimeter = (scale factor)*(old perimeter)
New perimeter = (5/3)*(old perimeter)
New Perimeter = (5/3)*(21)
New Perimeter = (5/3)*(21/1)
New Perimeter = (5*21)/(3*1)
New Perimeter = 105/3
New Perimeter = 35 inches
