Help please

I solved this using coordinates:

X = (1,0)

Y = (0.924328, 0.471208)

Z = (1.222783, -1.147542)

W = (0.924328, -0.471208)

==> angle BCD = 75 degrees

Let Y, X, and W be three consecutive vertices of a regular 18-gon. A regular heptagon is constructed on Line XY,  with a vertex Z next to X. Find angle YZW, in degrees.

Angle YZW = 80 degrees