Answer
The slope has unit: billions of dollars per year
The operating expense has grown by $0.8$ billion each successive year.
Work Step by Step
The unit of $E$ is billions of dollars,
the unit of t is years (after 2000)
The slope has unit: billions of dollars per year
In the model found in part (a), $E=0.8t-2.8$,
the slope equals $0.8.$
Interpretation:
The operating expense has grown by $0.8$ billion each successive year.
