The main foundation of algebra is to always to find missing patterns in numbers. By finding the missing patterns we can equate the left hand and right-hand sides of the equations to find the unknown variable. A variable is the unknown quantity in the equation. Therefore, a variable is the quantity which does not have a fixed value.
If we take the side of each square as ‘’. The perimeter of the square is . Whereas the area of the square is .
If we take the side of a triangle as ‘’. Then the perimeter of the triangle is .