The area of a rectangle is $96 cm²$. If the breadth of the rectangle is $8 cm$, find its  perimeter. 

We are given a rectangle of area,  $96c{m}^2$ and breadth as $8cm$.

For finding the length, we use the expression for calculating the area of rectangle which is:

$Area=length\times breadth$

Substituting the known values, we get:

$96=length\times 8$

simplifying which we get:

$length=12cm$

Now, we will use this length in finding the perimeter by the expression:

$P=2(length+breadth)$

Substituting the values, we get:

$P=2(12+8)$

$P=2\left(20\right)cm$

or we can say:

$P=40 cm$

Thus, the required perimeter of the rectangle is found to be: option (A) $40 cm$.