Polynomial Long Division

A high school student was at a soccer game and wanted to figure out how many people, per average, came to watch the high school soccer games. The total number of people who watched the high school soccer team play can be expressed as the function $f(x)= 6x^{3}+30x^{2}+24x$. The number of games the soccer team played can be modeled as $g(x)=x+4$. If $x$ is the number of years since $2016$, how many people, on average, came to watch one soccer game on $2018$?