Rotating 270 degrees counterclockwise about the origin is the same as rotating 90 degrees clockwise about the origin, which can be expressed in coordinate notation [tex](x,y) \longrightarrow (y, -x)[/tex].
So, the vertices of the image are:
[tex]U(4,0) \longrightarrow U'(0, -4)\\\\T(5,0) \longrightarrow T'(0, -5)\\\\S(5,-1) \longrightarrow S'(-1, -5)\\\\R(4, -1) \longrightarrow R'(-1, -4)[/tex]
