7. For the presidential elections from 1980 to 2008, the votes cast for the Democratic candidate can be modeled by
D(x) = 0.00230x³ - 0.0625x² + 1.17x +34.9 where x is the number of years since 1980 and D(x) is the number
of Democratic votes cast in millions. The votes cast for the Republican candidate in these elections can be modeled
by R(x) = -0.00140x4 +0.0809x³-1.41x² +7.29x + 43.5 where x is the number of years since 1980 and R(x)
is the number of Republican votes cast in millions. Write a model for the total Democratic and Republican votes
cast in the presidential elections from 1980 to 2008, and use it to estimate the total Democratic and Republican
votes cast in the 2000 elections.