Four students want to have their picture taken together. They will stand side-by-side for the picture. In how many different ways can the four students be arranged to take a picture? Show your work, please :')

What is the difference between regular convex and concave polygons

Mozart lenses inc. recently introduced seelites, a thinner lens for eyelasses. of a sample of 800 eyeglass wearers, 246 said they would purchases their next pair of eyeglasses with the new lenses. lenses inc. estimates that the number of people who purchase eyeglasses in a year is 1,700,000. most eyeglasses wearer buy one new pair of eyeglasses a year. what is the annual sales potential for the new lenses.

If there is 20 dogs in the shelter and 5 dogs get homes, and then 43 more dogs come. how many dogs are there in the shelter?