Which of the following equations is equivalent to the slope formula

The parabola x= √y-9 opens: a.)up b.)down c.)right d.)left

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

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