Answer:
0.5 X 15 X 20 = 150m squared
150 X 2 = 300m squared (that's the two triangles done)
25 x 7 = 175m squared (front)
15 X 7 = 105m squared (base)
20 X 7 = 140m squared (back)
now add them all together
300 + 175 + 105 + 140 = 720
SA = 720cm squared