Draw a circuit diagram and truth table:
Y = A + (B -C)
C = ~A + (AB)​

Ab c d e f g h i j k l m n o p

Hypothesis: volumes of both figures are equal.the volume of  figure 1 is: .the volume of figure 2 is: .since , you can conclude that and . so, .volumes of figures are equal only when an angle in the basis is right (then figures will be the same), in another cases volume of figure 1 is less than volume of figure 2.the hypothesis was not correct in all cases.