You can read posting Sarin learns Perimeter, Area and Volume in school(Math Concept) to learn the concept of perimeter, area and volume.
Lower primary school mathematics question LPQ34
Find the perimeter of the figure below.
From the above diagram,
a1 + a2 + a3 + a4 = 10cm
b1 + b2 + b3 + b4 = 12cm
The perimeter of the figure = 10 + 10 + 12 + 12 = 44cm