If you look at the two triangles, you will see each side has a different number of lines on them. Each set of lines corresponds to the same set of lines on the other triangle.
So since side IH has one line the side on the other triangle with one line would be congruent. So that would be line ML.
Also if there are not lines on every side then you could identify the triangle by the red square in the corner meaning that that is a right angle (90 degrees.)
