Final answer:
The question lacks details about the figure in question. Both Matt's and Cassie's methods for calculating volume require further context; we need to know the shape of the figure to determine the correct method and answer.
Step-by-step explanation:
The question seems to refer to finding the volume of a composite figure, although the necessary details about the figure are not provided in the question. Matt's method of finding volume by multiplying three dimensions suggests that he is treating the figure as a single rectangular prism, which would only be correct if the figure is indeed a single prism with those dimensions. Cassie's method of adding two separate volumes suggests she is viewing the figure as composed of two separate prisms, which would be the correct method if the figure is a composite made of two prisms. Without additional information about the figure, it is impossible to determine which student, if either, is correct. Regardless, in order to provide an accurate answer to this question, we would need a clear description or image of the composite figure.