Look at the figures. how can you prove these triangles are congruent?

You can use the Side-Angle-Side Postulate.

Step-by-step explanation:

The Side-Angle-Side (or SAS) Postulate basically states that if two sides of two triangles and the included angle are congruent, the two triangles are congruent.

"image"

step-by-step explanation:

in most of these problems, the notation is that the point with a "prime" is the image of the point without. that is, b' is the image of b.

here, there is no dilation or reflection. there is simply translation (with no direction shown). which figure you call the "preimage" and which one you call the "image" is up to you. as a matter of convention, the naming is as described above.