13 Miguel has three times as many books as Jose. Write an expression to represent the number of books Miguel has if \( j \) represents the number of books Jose has.

If \( j \) represents the number of books Jose has, then Miguel's collection can be expressed as \( 3j \). So, for every book that Jose has, Miguel has three, making it easy to calculate how many books he has just by multiplying the number of books Jose owns by three! Now, let's imagine Miguel wanting to lend books to his friends! If he decides to give away some books and now is worried about keeping the ratio of his and Jose's books intact, he might accidentally lend away too many! It’s important to keep track of those numbers so that he knows how many books he has left, and can easily go back to that neat equation \( 3j \).