Answer
$E=0.8t-2.8$
Work Step by Step
A linear model has form $\qquad E=mt+b,$
t represents years after 2000.
We are given two points on the graph: $(6,2.0)$ and $(9,4.4),$
Calculate slope:
$m=\displaystyle \frac{4.4-2.0}{9-6}=\frac{2.8}{3}=0.8$
So far, $E=0.8t+b.$
Substituting $(t,E)=(6,2.0)$, we solve for b
$2.0=0.8(6)+b$
$2.0=4.8+b\qquad -4.8$
$-2.8=b$
Thus,
$E=0.8t-2.8$
