Final answer:
The total cost of books varies directly with the number bought, represented by the equation t = $6.98 × b. Using this, we calculate that William, who bought 4 books, spent $27.92.
Step-by-step explanation:
Part A: Finding the Total Cost of Books
To find the total cost of any number of books, we need to establish a linear equation that relates the total cost to the number of books bought. Since the cost varies directly with the number of books, we can write the equation in the form t = kb, where t represents the total cost, b represents the number of books bought, and k is the constant of proportionality (the cost per book). To find k, we use the information that Georgia spent $62.82 for 9 books:
k = total cost / number of books = $62.82 / 9 books
Calculating this, we get:
k = $6.98 per book
So, the equation to find the total cost for any number of books is:
t = $6.98 × b
Part B: Calculating William's Total Cost
Now that we have our equation, we can calculate the cost for William, who bought 4 books:
t = $6.98 × 4
t = $27.92
Therefore, William spent $27.92 on books.