the hardcover version of a book weighs 7 ounces while its paperback version weighs 5 ounces. Forty-five copies of the book weigh a total of 249 ounces.

Keywords: System of equations, variables, hardcover version, paperback version, books For this case we must construct a system of two equations with two variables. Let "h" be the number of hardcover version books, and let "p" be the number of paperback version books. If the hardcover version of a book weighs 7 ounces and the paperback version weighs 5 ounces, to reach a total of 249 ounces we have: [tex]7h + 5p = 249[/tex] (1) On the other hand, if there are Forty-five copies of the book then: [tex]h + p = 45[/tex] (2) If from (2) we clear the number of books paperback version we have: [tex]p = 45-h[/tex]As each paperback version book weighs 5 ounces, to obtain the total weight of the paperback version books, represented by "x" in the table shown, we multiply[tex]5 * p = 5 (45-h)[/tex]So, [tex]x = 5 (45-h)[/tex]Answer: [tex]x = 5 (45-h)[/tex]Option D