Divide this polygon into 4 shapes (3 triangles and 1 rectangle)
Area of left triangle: 1/2(2)(5) = 5
Area of rectangle: 3 x 5 = 15
Area of the top triangle on the right: 1/2 (2)(4) = 4
Area of the bottom triangle on the right: 1/2 (3)(4) = 6
Area of polygon = 5 + 15 + 4 + 6 = 30
Answer
30 square units