Calculate the base area first:
The base area is formed by 3 rectangles:
Area of a rectangle = LEnght x width
Rectangle Area 1 = 2 x 2 1/2 = 5 ft2
Area 2 = 3x 2 1/2 = 15/2 ft2
Area 3 = 9 x 7/2 = 63/2 ft2
Add all the areas :
Total area = 5 + 15/2 + 63/2 = 44
Volume = base area x height = 44 x 1 1/4 = 55 ft3