Answer: Triangle 1 is the image of triangle 2 reflected over the y-axis
Triangle 2 is the image of triangle 3 reflected over the x-axis.
Reflecting triangle 4 over the y-axis results in triangle 3.
Explanation:
Triangle 1 is across from triangle 2. If you make the triangles bisect, they touch the y-axis.
Triangle 2 is above triangle 3. If you make the triangles bisect, they touch the x-axis.
If you "mirror" triangle 4 over the y-axis, you make the same shape then rotate it 90 degrees and put it the same distance from the y-axis.
I can't really explain it that good without touching the picture but its kinda just a mirror image.
You translate it (a congruent shape that is on a different axis and is the same distance from that axis) and rotate is 90 degrees