Answer:
8 < x < 22
Explanation:
The triangle inequality theorem tells us that if two sides of a triangle are known, the side length of the 3rd side would be in between the sum and difference of the side lengths of the other two sides.
If the 2 known sides of a triangle are "a" and "b", and the unknown side is "x", we can say that (given a > b):
a - b < x < a + b
In this problem, the 2 known sides are 7 and 15 units, the third side is "x", so:
Sum = 7 + 15 = 22
Difference = 15 - 7 = 8
Thus,
Difference < x < Sum
8 < x < 22