A square has four equal sides a, so the perimeter is 4a.
\(4a=20 \\
a=\frac{20}{4} \\
a=5\)
The side of the square is 5 ft long.
The length is increased by 2 ft -> 5+2=7 ft.
The width is decreased by 1 ft -> 5-1=4 ft.
The new figure is a rectangle with the dimensions 4 ft x 7 ft.
The area of a rectangle is the product of the length and the width.
\(A=4 \times 7=28\)
The area of the new figure is 28 ft².
