And that you have another angle, so so let me put some letters here again, and I'll start re-using letters, so this is 'A', 'B', 'C', and you have another angle that looks like this, that looks like this, I already used 'C', that looks like this notice and let's say once again that this is 50 degrees, and this right over here is 130 degrees, clearly angle DBA plus angle ABC, if you add them together, you get 180 degrees.