4) James has \( \$ 18 \) to buy books that cost \( \$ 4.50 \) each. James can buy \( b \) books in total. Which equation represents this situation? \( \begin{array}{llll}\text { a) } 18 b=4.50 & \text { b) } 4.50 b=18 & \text { c) } b+4.50=18 & \text { d) } b+18=4.50\end{array} \)

To determine how many books James can buy with his budget of $18, we need to consider the cost per book, which is $4.50. The equation that represents the relationship between the total amount James has, the number of books he can buy, and the cost per book is \( 4.50b = 18 \). Here, \( b \) represents the number of books that James can purchase. Now, if he were to buy more than 4 books, his total cost would exceed $18, leading to a fun scenario where he might have to start negotiating with the bookstore or opt for a used book section! So, stick to the affordable limit to keep your wallet intact!