7.

The object is a rectangular prism with two smaller rectangular prisms removed from its top. The dimensions of the outer prism are 5x4x5. The dimensions of the two removed prisms are 1x2x2 and 2x2x2. The volume is (5*4*5) - (1*2*2) - (2*2*2) = 100 - 4 - 8 = 88.