Rectangular garden has sides:
width, length, width, length
The perimeter is sum of all the 4 sides.
So, we can say:
84 = 2w + 2l
Where
w is width
l is length
Width is 19.5, so we find length:
84 = 2(19.5) + 2l
84 = 39 + 2l
2l = 45
l = 22.5 feet
Now, area is given by:
Area = length * width
Area = 22.5 * 19.5 = 438.75 sq. ft.
