so hmm notice the picture below
the triangular prism, is really just 3 rectangles and 2 triangles, stacked up to each other at the edges
now, just get the area of the triangles and the rectangles, and add them up, and that's the surface area of the triangular prism
now, what's the length "x"? well [tex]\bf x^2=5^2+7^2\implies x=\sqrt{25+49}\implies x=\sqrt{74}[/tex]
