Cassandra calculated the total volume of the figure below. A rectangular prism has a length of 7 inches, width of 6 inches, and height of 7 inches. A rectangular pyramid has a base of 6 inches by 7 inches and a height of 3 inches. Total volume = V of prism – V of pyramid       = Bh - Bh       = (7)(6) (7) – (7)(6)(3)       = 294 – 126       = 168 square inches What mistakes did Cassandra make? Check all that apply. She used square units instead of cubic units. In calculating the volume of the pyramid, she did not multiply by 1/3. She incorrectly identified the shapes composing the total figure. She subtracted the pyramid volume instead of adding it. She should have multiplied the dimensions of the prism by 1/3.