At a book fair, a tote bag costs $5 and any book b costs $3.50 each. Maria got a tote bag and some books, spending a total of $19.
Write an equation for this situation, and solve for the number of books b that she bought.
O $5 + $3.50b = $19, b = 4 books
O 5b + $3.50 = $19, b = 3.1 books
O $5 + $3.50b = $19, b = $4
O $3.50b - $5 = $19, b = $6.86