Left side:
All three angles of one triangle are congruent to all three angles of the other triangle, so by AA, the triangles are congruent.
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Right side:
30/5 = 6
24/4 = 6
18/3 = 6
Since all side lengths of one triangle are proportional to the corresponding side lengths of the other triangle, then by SSS Similarity, the triangles are congruent.
triangle ABC is similar to triangle DEF