Answer:
5 < x <21
Step-by-step explanation:
The side lengths of a triangle :
The sum of two side lengths selected at random must be bigger than the third side length and their difference must be smaller than the third side length
If we call the third side x than
x must be smaller than 13 + 8 and x must be bigger than 13 - 8 which means
5 < x <21
