Use a projector. Great. Then solve 3 · y and 5 · x + 2. Don't know how to use the projector? There's videos about it, but I'll teach you. Your projector has a hole. Mark the point of the vertex..
Wait, I don't know how to explain this.. Now let's pretend that you already have measured the angles. Now you might should divide it. C [divided by] 3 = y. For D, it'll be a little different. D [divided by] 5 - 2 = x. (Sorry can't make a division sign my keyboard doesn't have it) Now that's your answer(s). Bye.