Answer
$y=1.2 \ \text{billion}$
Work Step by Step
We plug in 18 since the current year is 2018:
$y=-.04(18)+1.62$
Now, we use PEMDAS, a method for simplification. This acronym reminds us that we must first address parentheses, and then exponents. Next, we address multiplication and division, going from left to right. Lastly, we simplify addition and subtraction from left to right. This gives:
$y=1.2 \ \text{billion}$
