What will be the breadth of the cuboid, with length and height as $20cm$ and $5cm$ respectively, which has the same volume as the cube of side $20cm$?

We are given a cube of side: $20cm$

Now, we have to find the dimensions of the cuboid having the same volume as the given cube.

We know the volume of cube is found by:

$Volume={\left(side\right)}^3$

So, the volume of the given cube is:

$Volume=20cm\times 20cm\times 20cm$

Simplifying which, we get:

$Volume=8000c{m}^3$

Thus, the cuboid will also have the volume $8000c{m}^3$.

Using the formula for volume of cuboid, we get:

$Volume=l\times b\times h$

Now, substituting the volume, we get:

$8000c{m}^3=l\times b\times h$

Substituting the height and length, we get:

$8000c{m}^3=20\times b\times 5$

separating variables both sides, we get:

$b= 80cm$

Thus, the required breadth of the cuboid is found to be option (D) $80cm$.