Which of the following could not be a value of n? side lengths of 9 and 13
a. 7
b.10
c. 13
d. 22

The correct answer here would be D. And that is because, in a triangle, the sum of 2 of the sides has to be greater than the third side for all sides.  If we add 22 and 13 we get 35, and 35 is greater than 9, for sure. But if we add 13 and 9 we get 22 which is not greater than the third side length of 22; it would be collinear with the side length and it has to be greater than the side length.