To find the new coordinates, we just have to use the given rule
[tex](x,y)\rightarrow(x,y-2)[/tex]Let's apply it to each vertex
[tex]\begin{gathered} A(2,10)\rightarrow A^{\prime}(2,10-2)\rightarrow A^{\prime}(2,8) \\ B(3,-4)\rightarrow B^{\prime}(3,-4-2)\rightarrow B^{\prime}(3,-6) \\ C(-3,1)\rightarrow C^{\prime}(-3,1-2)\rightarrow C^{\prime}(-3,-1) \end{gathered}[/tex]