perimeter of rectangle is calculated by taking the sum of all the sides of the rectangle. In rectangles the 2 opposite sides are equal length - 3x - 1 breadth - 3x - 3 the formula used to calculate perimeter for rectangle perimeter = (2 x length) + (2 x breadth) substituting length and breadth perimeter = {2 x (3x - 1)} + {2 x (3x - 3)} = 6x - 2 + 6x - 6 = 12x - 8 therefore correct answer is b.12x-8
