for the first one you have a vertical angle. Vertical angle is basically any 2 lines who intersect each other. The opposite sides will be congruent.
So in this case
2x+8 and 110 are oppostie sides.
2x+8=110
Which is x= 51
#2
For the second one you have supplementray angles
Now for supplementary angles its basically 2 angles added up that form a straight line And 180 degress is always the measure of a straight line. SO in this case we do
9x+12x+75=180
Which is x=5
#3
This is also a vertical angle pair and their congruent just like #1
