Answer:
400
Step-by-step explanation:
The surface area is found when adding the areas of all the squares in the prism. 5x10=50, and we have that square twice, so 100. Again, 5x10=50, and we have that twice, so another 100. Then, 10x10, which is 100, and we have two of those, so 200. 100+100+200=400
Hope that helped, have a nice day!
