[填空题]
Trapezoid PQRS is translated by 3g2 zpul k1-gp )2+ .k+cyr0+a4dkkf xmrjvva the vector $\left(\begin{array}{c}-7 \\ 2\end{array}\right)$ , then vertically stretched by a scale factor of $\frac{5}{3}$ and then reflected in the x -axis.
1. Determine a single transformation that maps the trapezoid PQRS to its image. Give your answer in the form $\mathbf{x}^{\prime}=\mathbf{A x}+\mathbf{b}$ The area of the image is equal to k times the area of the trapezoid PQRS.
2. Find the value of k . $\frac{a}{b}$ a = b =
