A store sells hardcover books for $8 and paperback books for $5. You buy 9 books, represented by the equation x + y = 9, where x is the number of hardcover books and y is the number of paperback books. The equation 8x + 5y = 54 represents the total cost. How many of each type of book did you buy?

Abag contains 3 red marbles, 2 blue marbles, and 2 green marbles. one marble is picked, then another marble. assume that the selections are made with replacement. a) find the probability of picking two red marbles with replacement. b) find the probability of picking a red marble and a blue marble. assume the selections are made without replacement. c) find the probability of picking two red marbles without replacement. d) find the probability of picking a red marble and a blue marble without replacement.