Since they are similar triangles, they are just enlarged versions of each other. This means that the left-most angle of triangle XYZ is also 35°.
Angles in a triangle add up to 180°, so we can find the missing angle by subtracting the two known angles from 180.
180 - 70 - 35 = 75
The right-most angle of triangle XYZ would be 75°.
Hope this helps!