Since the triangles are similar, they have same angles. The sum of the angles of the inside of a triangle is 180º.
With those two informations, we can write the following equation:
[tex]3x+6x+90=180[/tex]
Solving for 'x':
[tex]9x+90=180\Rightarrow9x=90\Rightarrow x=\frac{90}{9}=10[/tex]
With the value of x, we have the value of the angles.
They are 60º and 30º.
