Answer:
It will be 4 hours until the temperatures are the same
Explanation:
Let
represent the temperature in Coldspot in
hours and
represent the temperature in Frostberg in
hours.
From the question,
The temperature in Coldspot is -7° and is increasing 2.5° per hour, then we can write that

Also, from the question,
The temperature in Frostberg is 19° and is decreasing 4° per hour, then we can write that

To determine how long it will be until the temperatures are the same, that is when
will be equal to
, we will equate the two equations and determine
.
will give the number of hours until the temperatures are the same.


Then,



∴

Hence, it will be 4 hours until the temperatures are the same.