Answer:

Explanation:
The surface of a rectangular prims is defined as

Where
is length,
is width and
is height.
In this case, we have a figure formed by two rectangular prism. We are gonna call Surface 1 to the bottoming prism.
Its diemensions are:

So, the Surface 1 is

Now, the dimensions of Surface 2 are

Replacing all values, its surface is

Therefore, the total surface of the whole figure is
