Question

Karen bought some books. She spent a total of $71 after a discount of $5 off her total purchase. Each book cost $4. How many books did she buy? Write an equation that could be used to answer the question above. First, choose the appropriate form. Then, fill in the blanks with the numbers 71, 5, 4, and b to represent the number of books.

a) 4b - 5 = 71
b) 4b + 5 = 71
c) 5b - 4 = 71
d) 71 - 4b = 5

Answer 1

Karen bought 19 books. The correct equation to determine the number of books is 4b - 5 = 71, where 4 represents the cost per book and b is the number of books bought.

Step-by-step explanation:

To determine how many books Karen bought, we need to find the original total price before the discount and then divide that by the cost per book. Since Karen spent a total of $71 after a $5 discount, the original total before the discount was $71 + $5. Therefore, we can set up the following equation where b represents the number of books Karen bought:

4b - 5 = 71

Each book costs $4, so 4b represents the total cost of the books before the discount. The $5 discount is subtracted from the total cost, hence the -5. The equal sign followed by 71 represents the final amount Karen spent after receiving the discount. So, to solve for b, we would add 5 to both sides of the equation to isolate the 4b term:

4b - 5 + 5 = 71 + 5

4b = 76

Now we divide both sides by 4 to solve for b:

b = 76 / 4

b = 19

Karen bought 19 books.