Answer:
ΔBAC ~ ΔZYX
Explanation:
If we name the vertices in the order that gives segments in order of least-to-greatest length, then we will have named corresponding vertices in the two triangles. That is what we want for a similarity statement.
In triangle ABC, the segments in the order we're using are ...
40 (BA), 50 (AC), and 60 (CB) . . . we can call this ΔBAC
In triangle XYZ, the segments in the same order are ...
30 (ZY), 37.5 (YX), and 45 (XZ) . . . we can call this ΔZYX
Then the similarity statement can be written ...
ΔBAC ~ ΔZYX
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Additional comment
Once we identify corresponding vertices (B, Z), (A, Y), (C, X), we can list them in any of 6 different orders to write similarity statements.