Sense a triangle with with perfect angles = 60° per angle, and the only measurement we really have is x which is 90°, so that means it shifted to the left by 30°, so we can find the y now by just taking off 30° which would just make y = 30° then we’re left with z and we can now just find out we have left for a because we have 2 angles confirmed which would make z = 60°.
60 + 30 + 90 = 180 = total degrees in a triangle
X=90
Y=30
Z=60