3 part question that I don't understand

Question

Assume the united States' national debt can be estimated with the model y+ 2.07596(1.0831)x, where x represents the number of years since 1900and Y represents the debt in billions of dollars, when did the debt pass $1 trillion ($1,000 Billion)?

 

Answer 1

1000 < 2.07596(1.0831)^x

481.7048498 < 1.0831^x

ln 481.7048498 < x ln 1.0831

(ln 481.7048498) / ln 1.0831 < x

 

Can you calculate?