Answer:
A.) 5b+4=89
B.) 17 books
Step-by-step explanation:
To find A.), we must create a linear equation. Let b be the number of books Sam ordered. We write 5b because each book is 5 dollars. Then we add 4 dollars to the equation to represent the shipping fee. Then we write "equals to 89", because it says that is the total cost. So we get the equation 5b+$4=$89
To find B.), we must solve the equation. Isolate the variable, by subtracting 4 from both sides. We then get 5b=$85. Now we divide by 5 to get only the variable and to get rid of the coefficient. We get b=17. So Sam bought 17 books.