For this problem, we can say that corresponding angles are congruent, or the same, this also means that their angle measures have to be the same. Then, our equations for our angles will be vertical angles, which means that they must equal each other. So we would then write our equation as 3x+20=4x+10 or 4x+10=3x+20. Then, to combine like terms, we will subtract 3x from both sides, resulting in x+10=20. Then we will subtract 10 from both sides, resulting in x=10.
