Could somebody solve this with a explanation

608cm^2

Step-by-step explanation:

So, the surface area of any shape is the area of each and every shape added together.

So, for this you'll be using the area formulas for triangles and for squares.

(Area of a triangle, Area of a square )

Instead of adding (in my opinion) it's easier to multiply if you have two shapes of the same dimensions* (*if they don't have the same dimensions, you have to add. You can't multiply them because they aren't the same).

Fortunately, the two triangles are the same and the boxes on the top and bottom are the same as well.

So, the final surface area equation is going to look like this:

<- the subscripts on the lw's are to distinguish that one pair is specific to one set of numbers while the other is specific to another pair. they aren't necessary, really you could just skip this and plug in values.

* by the way, on the first step, the 2 in        

                                                                front of the 1/2 cancels it out so I

                                                                did that without showing.

608 is your answer.

36

Step-by-step explanation:20% of 30 is 6 so you add 6 on 30