SOLUTION: Mrs. Morris came back from her vacation and found that all of her 35 books has been checked out by students in her class. She said to her students, "I know for sure that at least

Let n be the most possible number of students in the class under given condition.


Then in the worst case they checked out  2n + 1 of her books.


So, our equation to find "n" is


    2n + 1 = 35.


It gives  n =  = 17.


ANSWERE.  There were 17 students in the class, at most.