Disposable income, the amount left after taxes have been paid, is one measure of the health of the economy. Using U.S. Energy Information Administration data for selected years from 2015 and projected to 2040, the U.S. real disposable income per capita (in dollars) can be approximated by the equation
I = 707.6t + 39,090
where t is the number of years after 2015.
(a)
What t-value corresponds to 2022?