Please help and give step by step explanation

Complex numbers multiply √-4 * √-25 and show all intermediate steps. alternative notation is sqrt(-4) * sqrt(-25).

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

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