ANSWER:
310 cm^2 (Don't ever forget the units) for the full surface area
STEP BY STEP:
I'll give you the area of the full thing.
First we will get the little square on the one side:
5 x 4 = 20
We got one side out of 8 sides.
Side 2:
10 - 5 = 5
5 x 4 = 20
Side 3:
5 x 4 = 20
Side 4:
5 x 4 = 20
Side 5:
5 + 5 = 10
10 x 4 = 40
Side 6:
5 + 5 = 10
10 x 4 = 40
Side 7:
10 - 5 = 5
5 x 5 = 25
5 x 5 = 25
5 x 5 = 25
25 + 25 + 25 = 75
Side 8:
10 - 5 = 5
5 x 5 = 25
5 x 5 = 25
5 x 5 = 25
25 + 25 + 25 = 75
ADD ALL SIDES TOGETHER:
75 + 75+ 40 + 40 + 20 + 20 + 20 + 20 = 310