Please help me solve these 3 problems relating to geometry of a circle.

1) ABCDEF is a hexagon inscribed in a circle. What is x + y + z?

http://i301.photobucket.com/albums/n...agonCircle.jpg

2) In this figure, find the value of angle ABC + angle ADC and figure out if ABCD a cyclic quadrilateral. Therefore, find angle BDC

http://i301.photobucket.com/albums/n...KiteCircle.jpg

3a) In this figure, AOB is the diameter. Prove that points OAMP are concylic.

3b) Find two angles equal to angle OPA.

http://i301.photobucket.com/albums/n...leTriangle.jpg

Thanks for any help.