You will end up with equations for x, y, and z in terms of one unknown. (You don't have enough equations to get this to single values of x, y, z.) So simply put z = a. Then you have two equations for x and y. Solve them for x and y in terms of a.

And hey, we get the answers done when someone looks at them, not before. So whereas I know you're in a hurry you are simply going to have to be patient about it and not try to rush us. Please be more polite.

-Dan