In what year population given amount if model stays accurate

Question

Population of St. Petersburg, Florida (in thousands) can be estimated by function where x=70 corresponds to 1970.

g(x)=-127.9+81.91 ln(x) , (x>70)

a.) Evaluate population in 1973. Estimate population in 1984.

b.) If model remains accurate, in what year will population be 256,000?