​A rectangle has the perimeter of 30cm.

The width of the rectangle is 4cm.

Find the length of the rectangle.

​The length of the rectangle is: 

30 : 2 – 4 = 11 (cm)

Answer:  11cm

​A square has the perimeter of 84m.

Find the length of one side of this square.

​The length of one side of the square is:

84 : 4 = 21 (m)

Answer:  21m

​What is the perimeter of the figure below?

​What is the perimeter of the figure below?

​(4 + 4) × 2 + 3 + 3 = 22 (mm)

Answer:  22mm