Question 599475
Your question appears incomplete - there is no mention of angle B in the question. I have made a change to the question as i believe it should be - maybe you made an omission in copying or typing out the question.


The question as altered could be solved as follows.


First let us note the applicable theorem in Geometry : The angles of a triangle add up to 180 degrees.


Assume angle B is x degrees. Since we are given that angle A is twice angle B, angle A could be denoted by 2x.Since We are given that angle C is 30 degrees more than angle A, we can denote angle C by 30+2x.


Hence the total of all 3 angles of the triangle ABC could be denoted by 
2x + x + 30+2x which should be equal to 180 degrees.


i.e.  2x + x + 30+x= 180
i.e.  5x + 30      = 180
i.e.  5x           = 150
i.e.  x            = 30


Hence the angles of the triangle ABC are 60, 30 and 90 degrees respectively.