Answer:
800 sq in
Step-by-step explanation:
There are 6 sides:
2 are 20 x 8, which each have an area of 160
2 are 20 x 10, which each have an area of 200
2 are 10 x 8, which each have an area of 80
(2 x 160) + (2 x 200) + (2 x 80)
880 sq in (assuming all sides are closed and he is painting them all)