Can someone please help me solve this algebra question?

Question

The annual Gross Domestic Product (GDP) of a country is the value of all of the goods and services produced in the country during a year. During the period 1985-1999, the Gross Domestic Product of the United States grew about 3.2% per year, measured in 1996 dollars. In 1985, the GDP was $577 billion. I what year did/or will the GDP equal $3.6 trillion?

 

If you can, listing out the basic steps helps me understand it better, but if not it's completely ok. Thanks!

Answer 1

3600 = 577(1.032)^t      in billions

6.239 ≈ 1.032^t             divide both sides by 577

ln 6.239 = t ln 1.032

1.830 ≈ 0.031t

59 ≈ t