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 equation
h+p = 45
We 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 equation
7h+5p = 249
Together 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/-2
h = 12
There were 12 hardcover copies sold.
Substitute this into our first equation:
12+p=45
Subtract 12 from each side:
12+p-12 = 45-12
p = 33
There were 33 paperback copies sold.
Answer:
D. 5(45 – h) so the last choice.
Step-by-step explanation:
hope it helps! correct on edge :)
