Answer
a. $y-28.2=0.2(x-12)$ or $y-28.6=0.2(x-14)$
b. $f(x)=0.2x+25.8$
c. $28.2$
Work Step by Step
a. With the coordinates of the two points, we can get the slope as $m=\frac{28.6-28.2}{14-12}=\frac{0.4}{2}=0.2$. Thus the point-slope form of the line equation can be written as $y-28.2=0.2(x-12)$ or $y-28.6=0.2(x-14)$
b. Rewrite the last equation above as $y=0.2x-2.8+28.6=0.2x+25.8$ or $f(x)=0.2x+25.8$
c. For year 2020, we have $x=2020-2008=12$ and $f(12)=0.2(12)+25.8=28.2$ years old.
