Let's split into two rectangles; you are right!
But a correction:
The left side is 12 and 16 because 28-16 = 12.
Top rectangle area:
area = width x length
area = 24 x (28-16)
area = 24 x 12
area = 288
Bottom rectangle area:
area = width x length
area = 16 x (24-13)
area = 16 x 11
area = 176
Total area: 176 + 288 = 464
464÷9 = 51.56
51 tables because you can't fit half a table.
