# Question Video: Solving Word Problems Involving Ratio Mathematics

If 7 books cost \$14, use a ratio table to determine the cost of 8 books.

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### Video Transcript

If seven books cost 14 dollars, use a ratio table to determine the cost of eight books.

In this question, we need to consider the number of books and the cost. We will assume that each book cost the same value. We are told in the question that seven books cost 14 dollars. We are asked to calculate the cost of eight books. We can do this by finding the unit cost first. In this case, this is the cost of one book. The unit cost is equal to the total cost divided by the number of units.

In this question, we can calculate the cost per book by dividing 14 by seven. This is equal to two. Therefore, each book cost two dollars. We have divided the number of books and the cost by seven. We can now calculate the cost of eight books by multiplying two dollars by eight. Two multiplied by eight is equal to 16. Therefore, the cost of eight books is 16 dollars.

Finding the unit cost first allows us to solve problems like this using scaling. We can calculate the total cost of any number of books by multiplying the unit cost by the number of books.