For a triangular prism, the formula for volume is v=bh where b is the area of the base (72) and h is the height (20). 72x20=1440 so the volume is 1440 cm^3
As for surface area, you want to find the area of each of the faces. For the triangle faces the area is 72. For the three identical rectangle faces the area is 240. 240x3+72x2= 720+144=864cm^2
Hope this helped :)
