Lets find the area of the 2 rectangles on the left and right side. 8*7 (2) = 112 (Both rectangles in total) Now lets find the rectangles on the front and back. 13*7 (2) = 182 Now, the top and bottom ones. 13*8 (2) = 208 Add them all together. 112+182+208 = 502 The surface area is 502.
Wee you find the area off all the sides and add em all up. First, for the big side to find the area is lw so 13 * 7= 91mm and there are 4 of those sides so 91*4 = 364mm. Next, for the small sides, lw is 8*7=56 and there are 2 so 50*2 = 112mm. And finally you add them together 112+364= 476mm
