Four students, Bella, Mika, Sarah, and Evelyn, line up one behind the other. how many different ways can they stand in line?

You drop a rubber ball off the roof of a 50 meter high building onto a paved parking lot. it bounces back up with every bounce, but not quite all the way back up to you. after the first bounce it bounces back only 80 percent of the distance it was dropped from. the pattern continues, meaning after every bounce it comes up to just 80 percent of the previous maximum height. so if before the first bounce the height is 50 meters, what height does the ball reach after the fifth bounce? round your answer to one decimal place and chose the correct response from the choices below:

Two numbers have a sum of -19. one number is x. what expression represents the other number?

The given diagram shows the parts of a right triangle with an altitude to the hypotenuse. using the two given  measures, find the other four.