The mean to your problem is 87.5
Most of the time it will be Length x Width x Height.
The answer is true. We know this because 9^2 - 6^2 is 45.
This is a triangular prism.
The lateral faces are triangles; this means that the two bases are parallel to one another. This makes it a prism instead of a pyramid.
The bases being triangles makes it a triangular prism.
C. $135, 1/4 of 60 is 15 and add that on top of 60x2