The perimeter of a square is 20 ft. if you increase the length of the square by 2 feet and decrease the width by 1 foot, what is the area, in square feet, of the new figure?

Technically, you can't do that because a square has equal side lengths

The perimeter of a square is found by just adding the lengths of the sides together. Since the square has four sides you just divide 20 by 4 to get 5 the length of each side. Then just add 2 to 5 to get the length of 7 and then subtract 1 from 5 to get 4 for the width. The new figure is going to be a rectangle so to find its area it's just width x length. 7 x 4 = 28 ft^2