Please view the photo I have attached. What is the sample variance and what is the sample standard deviation?! PLEASE HELP

Which solid has two triangular bases and three lateral faces, each in the shape of a rectangle? triangular prism triangular pyramid rectangular prism rectangular pyramid

Ineed ! the person who answers and shows their work on they got the answer first will be marked the !

Adam plans to choose a video game from the section of the store where everything is 75% off. he writes the expression d-0.75d to find the sale price of the game if the original price is d dollars. gena correctly writes another expression, 0.25d, that will also find the sale price of the game if the original price is d dollars. use the drop down menus to explain each part of adams and rena's expression