Answer:
Nothing Changed
Step-by-step explanation:
at 7:30 it was −4°F and at 9:27 it was still −4°F.
However in-between the timelines +58° then it went down 58°
 
        
                    
             
        
        
        
The slope-intercept form of a line is:
y=mx+b, where m=slope and b=y-intercept (value of y when x=0)
First you must find the slope, or m value.
m=(y2-y1)/(x2-x1), which is the change in y divided by the change in x.  In this case:
m=(5--3)/(-4--1)
m=(5+3)/(-4+1)
m=8/-3
m=-8/3
So far our line is:
y=-8x/3+b, we can now solve for the y-intercept, or b, using any point on the line, I'll use (-4,5):
5=-8(-4)/3+b
5=32/3+b
15/3=32/3+b
15/3-32/3=b
-17/3=b
So now we know the value for both terms in our line:
y=(-8x-17)/3
        
                    
             
        
        
        
So if the whole area is 360 degrees, subtract 91 three times to get 87. divide that by 3 to get 29 degrees. 
g = 29 degrees