2 × 40
To solve it with the help of Diagram,
Draw a Rectangle having 8 rows and 5 columns. Draw a copy of this rectangle .You can draw rectangles of other dimension like (10 × 4 or 4×10, 5×8).
So, there will be total of 2 identical rectangles.
Each part of a rectangle = 1 object
So, there are 80 parts in all.
So , 2 × 40 = 80