Try to get the u’s on one side so for this to happen, you would subtract the four from both sides.
u - 4u = 7 - 4
combine like terms
-3u = 3
divide by -3
u = -1
She saved up a total of $82.60, and had to spend a total of $60.90, so she would have $21.70 left and need to save up another $180.40, hope this helps
Answer: Interval = [103,∞)
Explanation :
A medicine become ineffective if its temperature ever reaches 103 degrees Fahrenheit or more .
So, Interval becomes [103,∞)
i.e. semi-open or semi-closed interval as it includes 
So, we used closed brackets i.e. square brackets and
For '∞' we always use open brackets only.
Appositive is a noun that renames another noun right beside it. So the appositive phrase in this sentence is "my classmate".