The perimeter of the square is 12 cm. Increase each side by 2 cm. What is the perimeter of the resulting square?

The perimeter of a square is the sum of the lengths of all sides of the square.
If each side of the square increases by 2 cm, then the perimeter increases by 2 cm * 4 = 8 cm (since the sides are 4 and each has lengthened by 2 cm).
The perimeter of the new square is 12 cm + 8 cm = 20 cm
Answer: 20 cm.

Another way:
It is easy enough to find the length of one side of a square, since all sides in a square are equal.
Sides 4, divide the perimeter by 4:
12cm: 4 = 3cm is the length of each side of the square
Increase by 2 cm:
3 cm + 2 cm = 5 cm – the length of the side of the resulting square
We are looking for the perimeter – we add all 4 sides of the square:
5 cm + 5 cm + 5 cm + 5 cm = 20 cm