Answer:
6 Days
Step-by-step explanation:
Let the number of days be [tex]x[/tex].
Given:
Daily temperature decreased by 1.5 °F in each day.
So, the temperature decreased in [tex]x[/tex] days is [tex]1.5x[/tex].
Therefore the temperature decreased by 9 °F in [tex]1.5x[/tex] days.
The equation is [tex]1.5x=9[/tex]
[tex]x=\frac{9}{1.5}[/tex]
[tex]x=6[/tex]
The temperature decreased by 9 °F in 6 days.