The formula for the surface area of a rectangular prism is 2 (wl + hl + hw)
So first we multiply the width by the length. 12 x 4 = 48 Now we multiply the height by the length. 3 x 4 = 12 Now we multiply the height by the width. 3 x 12 = 36 Now we add all of our answers together. 48 + 12 + 36 = 96 And now we multiply it by 2. 96 x 2 = 192
So the surface area of the rectangular prism is 192.
