Answer:
7 hours
Step-by-step explanation:
We are given that
At sunset, the temperature=-5 degrees Fahrenheit
Each hour, temperature falling=2degrees Fahrenheit
We have to find time taken to reach the temperature -19° F.
Let x be the time time taken to reach the temperature -19° F
According to question
[tex]-5+x(-2)=-19[/tex]
Where we taking 2 negative because temperature decreases.
[tex]-5-2x=-19[/tex]
[tex]-5+19=2x[/tex]
[tex]14=2x[/tex]
[tex]x=\frac{14}{2}[/tex]
[tex]x=7[/tex]
Hence, it will take 7 hours for the temperature to reach -19° F.