#### Answer

$683.6$ billion dollars

#### Work Step by Step

We are given that $f(x)=.19x^{2}+5.67x+43.7$ can be used to approximate the amount of restaurant food-and-drink sales, where x is the number of years since 1970 and f(x) is the sales (in billions of dollars).
To estimate the sales in 2015, we will use $x=45$, because 2015 is 45 years after 1970.
$f(x)=.19(45)^{2}+5.67(45)+43.7=683.6$ billion dollars