This is the amount paid or charged for something?

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?

James was playing a game with his friends. he won 35 points. then he lost 15, lost 40 and won 55. how did he come out

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