Would anyone be able to find z and explain how they did it? in advance.

The answer is 29. If you look at the triangle on top of it, with the obtuse angle being 122 you can see that that triangle and DEF are the same. And because the degrees of a triangle is always 180 you can subtract 122 from 180:
 180
-122
That equals 58 and because there are two sides we need to divide 58 by 2:
58/2
this equals 29 so 
z = 29
:)