The perimeter of the square is 8cm. A rectangle was made from two such squares. Find the area of this rectangle.

The perimeter is the sum of the lengths of all sides.
Therefore, if the perimeter of one such square is 8cm, then side 8: 4 (sides of the square) = 2
The width of the resulting rectangle will clearly be 2cm.
And the length will be side (2cm * 2 (sides of the square) = 4
So, we got a rectangle whose sides are 4cm and 2cm (if you can’t imagine a rectangle of squares in your head, it’s better to draw a picture);
Rectangle area = a * b
a = 4
b = 2
Spr = 4 * 2 = 8 cm