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. Which value could replace x in the table?

Answer:33 copies were paperback and 12 were hardcover.Step-by-step explanation:Let h represent the number of hardcover copies and p represent the number of paperback copies.We know that the total number of copies was 45; this gives us the equationh+p = 45We know that each hardcover copy is 7 ounces; this gives us the expression 7h.We also know that each paperback copy is 5 ounces; this gives us the expression 5p.We know that the total weight was 249 ounces; this gives us the equation7h+5p = 249Together we have the system[tex]\left \{ {{h+p=45} \atop {7h+5p=249}} \right.[/tex]We will use elimination to solve this.  First we will make the coefficients of the variable p the same; to do this, we will multiply the top equation by 5:[tex]\left \{ {{5(h+p=45)} \atop {7h+5p=249}} \right. \\\\\left \{ {{5h+5p=225} \atop {7h+5p=249}} \right.[/tex]To eliminate p, we will subtract the equations:[tex]\left \{ {{5h+5p=225} \atop {-(7h+5p=249)}} \right. \\\\-2h=-24[/tex]Divide both sides by -2:-2h/-2 = -24/-2h = 12There were 12 hardcover copies sold.Substitute this into our first equation:12+p=45Subtract 12 from each side:12+p-12 = 45-12p = 33There were 33 paperback copies sold.