Answer: 98 < T < 105
Explanation:
Let S represent the elevation of Sakura's house.
Since Sakura's house is between 113 and 120, this can be expressed as
113 < S < 120
Ted's house (T) is 15 below Sakura --> T = S - 15
So subtract 15 from all three sides of Sakura's equation:
113 < S < 120
-15 -15 -15
98 < S - 15 < 105
⇒ 98 < T < 105