Ap calculus need help please

Statement: if two distinct planes intersect, then their intersection is a line. which geometry term does the statement represent? defined term postulate theorem undefined term

Suppose you are an avid reader and are looking to save money on the cost of books instead of paying about $20 for each book, you decide to look into purchasing a kindle for $120 you can purchase e-books for about $5 each 1. find the slope-intercept equation for the cost of the hard copy of books using x to represent the number of books 2. find the slope-intercept equation for the cost of the kindle with cost of e-books using x to represent the number of books

Annabelle's homework is 75% it took her three hours how long should she estimate it will take her to complete her homework.