Answer
There were about $9.7$ billion pounds of cheese produced in the United States in 2007.
Work Step by Step
2007 is 4 years after 2003 so $x=4$.
Substitute 4 to $x$ in the given equation to have:
$\\y=8.6(1.03)^x
\\y=8.6(1.03)^4
\\y=9.679375766
\\y\approx 9.7$