Answer
$-414720x^3$
Work Step by Step
Step 1. Use the Binomial Theorem, the general form of the term containing $x^r$ from the expansion of $(a+b)^n$ is given by:
$\begin{pmatrix} n\\r-1 \end{pmatrix}a^{r-1}b^{n-r+1}$
Step 2. With $n=10, r-1=3$, we get $r=4$ and the term is given by:
$\begin{pmatrix} 10\\4-1 \end{pmatrix}(3x)^{4-1}(-2)^{10-4+1}=-120\times2^7\times3^3x^3=-414720x^3$
