1. Quadrilateral $F$ under the mapping $f:(x, y) \rightarrow(x-1, y+2)$ has the image set as quadrilateral $F^{\prime}$. The area of quadrilateral $F$ is 6, then the area of quadrilateral $F^{\prime}$ is $\qquad$ .
1. 6 Explanation: The mapping $f$ translates quadrilateral $F$ 1 unit to the left and 2 units upwards, resulting in quadrilateral $F^{\prime}$. Therefore, the area of the shape remains unchanged, still 6.