Answer: x ∈ (10; +∞)
Explanation:
Since x isn't the longest side of the triangle, it is one of the shorter ones, so the sum of two shorter sides must be greater than the longest side of the triangle (that's the property):
x + 16 ﹥ 26
x ﹥ 26 - 16
x ﹥ 10 (x ∈ N)
x ∈ (10; +∞)
Let's say, I chose x = 20
Since x can be on either shorter side of the triangle, she can make 2 triangles (I think)