The rectangular base has an area \(20 \times 15 = 300\)
The triangles have an area \(20 \times 8 \div 2 = 80\)
Thus the area is \(300 + 80 = \color{brown}\boxed{380}\)
The rectangular base has an area \(20 \times 15 = 300\)
The triangles have an area \(20 \times 8 \div 2 = 80\)
Thus the area is \(300 + 80 = \color{brown}\boxed{380}\)