Not really a lot to do with this problem. All we need to do is use the formula from the Binomial Theorem to do the expansion. Here is that work.

\[\begin{align*}{\left( {9 - x} \right)^4} & = \sum\limits_{i = 0}^4 { {4 \choose i} {9^{4 - i}}{{\left( { - x} \right)}^i}} \\ & = {4 \choose 0} \left( {{9^4}} \right) + {4 \choose 1} \left( {{9^3}} \right){\left( { - x} \right)^1} + {4 \choose 2} \left( {{9^2}} \right){\left( { - x} \right)^2} + {4 \choose 3}\left( {{9^1}} \right){\left( { - x} \right)^3} + {4 \choose 4}{\left( { - x} \right)^4}\\ & = {9^4} + \left( 4 \right)\left( {{9^3}} \right)\left( { - x} \right) + \frac{{4\left( 3 \right)}}{{2!}}\left( {{9^2}} \right){\left( { - x} \right)^2} + \left( 4 \right)\left( {{9^1}} \right){\left( { - x} \right)^3} + {\left( { - x} \right)^4}\\ & = \require{bbox} \bbox[2pt,border:1px solid black]{{6561 - 2916x + 486{x^2} - 36{x^3} + {x^4}}}\end{align*}\]