Answer:
He is not painting the bottom or top meaning that he will paint 4 sides total, when there is a rectangular prism there are 6 sides and 3 pairs of 2 equal sides, so since there is a wall that is 9ft x 7 ft there is two of those, and since there is a wall that is 12 ft x 7 ft there are two of those as well. meaning that (7x9)·2=126 and (12x7)·2=168 when added we get 294. meaning that he needs to paint an area of 294 ft
