If you notice the tickmarks, that means all slanted sides are of length 2.5
now, a triangular prism, is just two triangles and three rectangles stacked up to each other, check the picture below, like so. So to get the area of it, simply get the area of the rectangles and the triangles.
now, notice, the triangles have a base of 4 and an altitude/height of 1.5.
the rectangles on the left and right sides are just 2.5 x 6 each.
and the rectangle at the base of the prism, is a 4 x 6.
thus, the area of the triangular prism is just