How do you calculate domain and range

Rearrange the formula c^2 = a^2 + b^2 for b

At school there are 526 students and 263 are girls about how likely is it that a randomly chosen student will be a boy

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