Answer
$$y=5~800~000x+248~000~000$$
Work Step by Step
First define the variables.
Let $x$ be the number of years since $2007$. So that for $2007$ the value of $x$ is $0$ and for $2012$ the value of $x$ is $5$.
Let $y$ be the number of megawatt hours.
So, the corresponding data values in ordered pair is - $(0,248~000~000)$ and $(5, 277~000~000)$.
We should write the linear model $y=mx+b$ using these two points.
Note, $b$ is an initial value that is $248~000~000$ in this case. So, only find the slope:
$$m=\frac{y_2-y_1}{x_2-x_1}=\frac{277~000~000-248~000~000}{5-0}=\frac{29~000~000}{5}=5~800~000$$
Hence, linear model becomes:
$$y=5~800~000x+248~000~000$$
