You could break down the shape and then get to the area but there is a better way.
The picture looks like a rectangle with a chunk pulled off it.
Let just imagine that it was a perfect rectangle.
Its dimensions would be 57 by 36 (20+16).
Perfect Rectangle Area = 57x36 = 2052

Now, let us find the area of the indent and subtract that from the previous area.
Indent Area = 16 x (57-15-15) = 16x27 = 432

Real Area = 2052
- 432
= 1620

answer = 1620
