please provide explanation on the question below

The national health expenditures are projected to grow at the rate of _ U.00581'+0.159 dt trillion dollarsfyear from 2002 through 2015. Here, 1:0 corresponds to 2002. The expenditure in 2002 was $1.60 trillion. 3) Find a function f giving the projected national health expenditures in year t. b) What does your model project the national health expenditure to be in 21115