<p>I got the right answer here, but are you supposed to assume that the triangles are isosceles triangles? I don't believe the question states it, so I took a leap of faith with this problem and assumed the triangles were all isosceles.</p>
<p>You don't need to assume anything.
They are asking you for the outside perimeter. Since the perimeter of a triangle is 30, and each side of the cube is 9, the "outside" perimeter is 21.</p>
<p>so, 21 x 4 = 84 (D)</p>
<p>Wow, stupid me. -_-</p>
<p>Thanks for the help. :)</p>