Explanation

Moment of force, $\vec{\tau} = \vec{r} \times \vec{F}$ [add image] $\vec{\tau} = (\vec{r} - \vec{r}_{0}) \times \vec{F}$ $\vec{r} - \vec{r}_{0} = (2\hat{i} + 0\hat{j} - 3\hat{k}) - (2\hat{i} - 2\hat{j} - 2\hat{k}) = 0\hat{i} + 2\hat{j} - \hat{k}$ $\vec{\tau} = (0\hat{i} + 2\hat{j} - \hat{k}) \times (4\hat{i} + 5\hat{j} - 6\hat{k})$ $\vec{\tau} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 0 & 2 & -1 \\ 4 & 5 & -6 \end{vmatrix} = -7\hat{i} - 4\hat{j} - 8\hat{k}$