Find the surface area of the composite solid.

Area of the bottom triangle = 1/2 x 10 x 8.7 = 43.5 cm²

Area of the 3 rectangles = 3(10 x 6) = 180 cm²

Area of the top triangle = 3 (1/2 x10 x 4) = 60 cm²

Total surface are = 43.5 + 180 + 60 = 283.5 cm²

283.5 cm²