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=51 represents the total cost. How many of each type of book did you buy?

Aprofessional hockey team has noticed that, over the past several seasons, as the number of wins increases, the total number of hot dogs sold at the concession stands increases. the hockey team concludes that winning makes people crave hot dogs. what is wrong with the hockey team's conclusion? a) it does not take into account the attendance during each season. b) it does not take into account the number of hamburgers sold during each season. c) it does not take into account the number of concession stands in the hockey arena. d) it does not take into account the number of seasons the hockey team has been in existence.