Answer: 2 < x < 16
The triangle inequality theorem says that if we have a triangle with sides a,b,c then
b-a < c < b+a
with b being longer than 'a'
In this case, a = 7 and b = 9 and c = x
so we have
b-a < c < b+a
9-7 < c < 9+7 .... replace a with 7, replace b with 9
2 < c < 16
2 < x < 16 .... replace c with x
So x can be any number between 2 and 16. The value of x cannot be equal to 2. Also, x cannot be equal to 16 either.