Answer:
c
Step-by-step explanation:

Given :7x+6=5(x+2)
Now We will use the distributive property to multiply 5 by x+2.
→7x+6=5x+10
We will Subtract 5x from both sides.
→7x+6−5x=10
We will Combine 7x and −5x to get 2x.
→2x+6=10
We will Subtract 6 from both sides.
2x=10−6
We will Subtract 6 from 10 to get 4.
2x=4
We will Divide both sides by 2.
x= 4/2
At last,We Divide 4 by 2 to get 2.
x=2
Keywords:
<em>System of equations, variables, hardcover version, paperback version, books
</em>
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:
(1)
On the other hand, if there are Forty-five copies of the book then:
(2)
If from (2) we clear the number of books paperback version we have:

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
So, 
Answer:

Option D