Sorry to bother, I've been searching for 4 hours for a solution to this and it feels like such a long time ago from when I did this in high school/uni, whichever it was, that my head is about to explode.
I don't know angle z nor ?; I know every other variable I've written there including y and w. The purpose of this is to find the angle at which the circle must be shot against the top wall so that it goes exactly to the point where the bottom left angle w is. The collision against the wall is perfecty ellastic so z = z. What am I missing so that I can find the angle z here? I think I need one more piece of information and I can come up with the equation but for the life of me I can't figure it out =( I must be forgetting some law of similar triangles.