A)
In order to find the percentage for the year 2010 using the linear model, we need to use the value x = 30 in the function f(x), because f(x) represents a linear model and x represents the number of years after 1980.
So, calculating f(30), we have:
[tex]\begin{gathered} f(x)=x+25 \\ f(30)=30+25 \\ f(30)=55 \end{gathered}[/tex]
Therefore the percentage is 55%.
