Irene R. answered 04/03/20
BS in Mechanical Engineering and Certified math teacher for 13 years
Let's use the variable x to represent the number of books he bought.
Since each book cost $7 and shipping was $6, we can write the following equation to represent the problem:
7x + 6 = 97
We can solve this equation using inverse operations:
7x + 6 = 97
7x + 6 - 6= 97 - 6
7x = 91
7x/7 = 91/7
x = 13
He bought 13 books.