Find the values of the angles x, y and z in the following figure.
In the figure, if AB = AC and AD || BC, then x, y and z are respectively = _____.
In the figure, x, y and z are the internal angles of ∆ABD. Line ED || AB and side AD is extrapolated to point P and the value of ∠EDP and ∠EDB are n and m, respectively. If x and z are 75∘ and 55∘ respectively, find the value of m + n.