Choose one of the following theorems and prove it: vertical angles are congruent, alternate interior angles are congruent, corresponding angles are congruent. demonstrate on a whiteboard. (just tell me how to write it on a whiteboard)

As can be seen from the figure above, when two lines intersect, four angles are formed. Each opposite pair are called vertical angles and are always congruent. The red angles ∠JQM and ∠LQK are equal, as are the blue angles ∠JQL and ∠MQK. Vertical angles are also called opposite angles.

20x+25= 30x +5
-20x -5 -20x -5
20 10x
10 10
x=2

go to the smallest number with no x so that would be 5 since it is a positive 5 you subtract.
so then you would put the 5 under the other number with no x in it. And then solve it so since it's 25 you would minus 5 from 25 that equals 20. then you would go to the other side and do the same so then it would be 30x-20x=10x then 20÷10=2 so your answer would be x=2