The angles are adjacent and x is equal to 20.
If you add (x+20) and 7x then you will get 8x+20. Then you have to set that equal to 180. By now the equation should be 8x+20=180. You then have to subtract 20 from both sides which will give you 8x=160. Then you divide both sides by 8, which gives you the answer of 20.
