Answer:
The two lines of reflection are
and

Explanation:
I will attach a file with the graph of the rectangle and the lines of reflection.
We know that RSTU is a rectangle with vertices at
,
,
and

The first step is to draw the vertices on the plane and them the rectangle.
The rectangle is a symmetrical figure. Therefore if we want to carry the rectangle onto itself using a line of reflection this line must goes through the centroid of the rectangle.
Given that we have a rectangle whose width is
and its length is
its centroid will be place at
.
Looking at the graph and using this information we find that the two lines of reflection are
and
.