Hey there!
Surface area is for three dimension figures, and measures the area and how much space and as aforementioned area is in the object. This shape is a rectangular prism, so the surface area formula is:
2(lw+wh+lh)
Surface area is just an adding of all of the areas of the sides. It's times two because just the parentheses cover half the object. Plug in values:
A = 2(6*17 + 6*9 + 17*9) =
2(6)(17) + 2(6)(9) + 2(17)(9) =
204 + 108 + 306 =
618
Hope this helps!