Are the following a solution for the inequality below?

Plz i want answer and i would appreciate it is is a b c or d

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

What effect would doubling all the dimensions of a triangular pyramid have on the volume of the pyramid? explain your reasoning.