Angles 1 and 2 have to equal 180° since they are supplementary.
So you put 3x+2x-25=180, you then add like terms. 5x-25=180 Then you have to isolate x, so you add 25 to both sides of the equation. 5x=205, then you divide both sides by 5. So your answer is x=41.
You can check to make sure by plugging in x for 41 .
Hope this helps!
