ANSWER
See graph
EXPLANATION
The given triangle triangle RST has vertices R(6, 6), S(3, –6), and T(0, 3).
A reflection in the y-axis has the mapping
[tex](x,y)\to (-x,y)[/tex]
This implies the image triangle will have vertices.
R(-6, 6), S(-3, –6), and T(-0, 3).
See attachment for graph.