75°
Since â–łABC is similar to â–łXYZ, that means that angle A equals angle X, angle B equals angle Y, and angle C equals angle Z. So let's look at the data we have.
Angle A measures 45° and angle C measures 60°. That means that angle B measures 180° - 45° - 60° = 75° since all triangles have 180° and we've been told the measurement of two of the angles. And since angle Y is equal to angle B (which we just calculated), that means that angle Y is also equal to 75°
