The formula for determinin the area of a parallelogram is expressed as
area = base x height
For the small parallelogram,
area = 20
base = 4
height = area/base = 20/4
height = 5
If two figures are similar, it means that the ratio of their corresponding sides are equal. Thus, we have
4/16 = 5/h
where h is the height of the big parallelogram. By crossmultiplying, we have
4 * h = 16 * 5
4h = 80
h = 80/4
h = 20
Thus,
Area of big parallelogram = 16 x 20 = 320 ft^2