Okay, to find the answer, you need an equation. So here we go...
Small angle = x
Large angle = 2x+6
Sum of the angles = 180°
The equation is now
2x+6+x=180
Simplify
3x+6=180
Now move the 6 to the there side (numbers together)
3x+6(-6)=180(-6)
3x=174
Now divide by 3 to solve for x
3x/3=174/3
X=58
That is the smaller angle.
Now for the large angle, just plug that number into the other equation
2(58)+6=?
116+6=122
That is your large angle.