SA of a triangle: 1/2(base * height)
SA of a rectangle: length * width
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SA of rectangle: 30 cm * 14 cm = 420 cm²
SA of top and bottom triangles: 2 * 1/2(30 cm * 20 cm) = 600 cm²
SA of side triangles: 2 * 1/2(14 cm * 24 cm) = 336 cm²
Add up all the SAs.
420 + 600 + 336 = 1,356 cm²