How does one 'Describe fully a single translation'?
My object has been reflected twice, do I just say 'reflected on x=_ then on y=_'?
Does the question say 'Describe fully a single transformation ...'?
When one reflection is followed by a second reflection in mirror-lines that are not parallel, this is equivalent to a rotation, whose centre is at the point where the mirror-lines meet, through twice the angle between them.
It sounds as if your mirror-lines are at right-angles, so the rotation will be through a half-turn.
Does that help to answer your question?
It can't just be a rotation, it doesn't make sense.
It is 'single transformation'
Here are the coordinates of the three triangles
A= 0,3 1,3 and 1,5
B= 3,0 3,1 and 5,1
C= 5,3 6,3 and 5,5
Describe the translation of A onto B. Is this a reflection around line y=x?
I was guessing what the answer might be, based on the incomplete information you gave me in your first post. You are right: the transformation that maps A onto B is a reflection in the line .
B is then mapped onto C by a rotation through anticlockwise, centre .
The single transformation that maps A onto C is a reflection in the line .