Answer:
94 square inches.
Explanation:
Surface area is the area around a surface. Thus, in order to calculate the surface area of a rectangular prism, we just need to add up the different faces of it.
There are 2 5x4 faces, 2 3x5 faces, and 2 4x3 faces.
Thus, we get 2*20 + 2*15 + 2*12 = 40 + 30 + 24 = 94 square inches.