It's an isosceles triangle, so the angles at the base are congruent:
[tex]m\anlge WXY=m\angle WZY[/tex]
The triangle XYW is a rectangular triangle.
We know that the sum of the measures of angles in a triangle is 180°.
Therefore we have the equation:
[tex]m\angle YWZ+90^o+17^o=180^o\\\\m\angle YWZ+107^o=180^o\ \ \ |-107^o\\\\m\angle YWZ=73^o[/tex]
Answer: 73
