The answer is " 768 square feet. ".
Total surface area of a triangular prism = width x height +(sum of sides + width) x length and here;
width = 10
height = 12
sides = 13
length = 18
= (10 x 12) + (13 + 13 + 10) x 18
= 120 + (36 x 18)
= 120 + 648
= 768 square feet.
The two triangles are congruent, so corresponding parts of the two triangles are congruent.
GH is corresponding to DE, so GH=DE=17
Its -1.5 or in other fraction form its -1 1/2.......hope that helps
5.40. It would be 5.38 but you round up to 5.40