I'll just give this a stab here.
You have an triangle. (It might help to draw one)
Pick an angle. The outside of that angle measures 130 degrees. The total is 180 degrees because the exterior creates a line with the base of a triangle.
So your interior is 50 degrees. That is ONE angle of the triangle.
The total angles of all triangles = 180 degrees.
180 - 50 = 130.
So the other two angles have to add up to 130, and one is 2/3 of the other.
2/3x + x = 130.
That's a huge mess to me.
THIS IS NOT THE FINAL ANSWER.
But if you know what to plug in for X, I think it'll be alright for you. If not, guess and check is what I was doing. I hope this helps.
