A businessman models the number of items (in thousands) that his company sold from 1998 through 2005 as N(x) = −0.1x^3 + x^2 − 3x + 8 and the average price per item (in dollars) as P(x) = 0.2x + 9, where x represents the number of years since 1998. Enter a polynomial R(x) that can be used to model the total revenue for this company.