The given coordinates of the vertices of the figure are:

Recall the coordinate rule for 90⁰ counterclockwise rotation around the origin:

Apply this rule to the first vertex, R(3,4):

Apply this rule to the other vertices to get:

Answers:
R'=(-4,3)
S'=(-4,10)
T'=(-8,10)
U'=(-8,3)