The ninth term of the series [tex]80,60,45.....[/tex] is [tex]50[/tex].
We need to determine the relationship between the consecutive terms of the series to evaluate the succeeding terms of the series.
How to find the terms in a series?
The difference between the first and second terms is [tex]60-80=-20[/tex].
The difference between the second and the third terms is [tex]45-60=-15[/tex]
So, the difference between the third and the fourth terms will be [tex]-10[/tex]. So, the fourth term will be [tex]45-10=35[/tex].
Similarly, the difference between the eighth and the ninth terms will be [tex]-15[/tex]. So, the ninth term will be [tex]35-(-15)=50[/tex].
Thus, the ninth term of the series is [tex]50[/tex].
Learn more about series here- https://brainly.com/question/12707471
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