The national debt of a South American country t years from now is predicted to be D(t) = 70 + 18t^4/3 billion dollars. Find D'(8).

D'(8) =

The national debt is increasing by _______ billion dollars per year after 8 years

Find D''(8)=

The rate of growth of the national debt is increasing by ________ billion dollars per year each year after 8 years